diff --git a/xslt/articles/xslt-article-Datacite.xslt b/xslt/articles/xslt-article-Datacite.xslt
index a6a49016..ed826437 100644
--- a/xslt/articles/xslt-article-Datacite.xslt
+++ b/xslt/articles/xslt-article-Datacite.xslt
@@ -9,37 +9,38 @@ Made by Shiraz Malla Mohamad member of zbmath Team-->
                 exclude-result-prefixes="#default">
     <xsl:output method="xml" indent="yes"/>
     <xsl:template match="/">
-            <resource xsi:schemaLocation="http://datacite.org/schema/kernel-4 http://schema.datacite.org/meta/kernel-4/metadata.xsd">
+        <resource xsi:schemaLocation="http://datacite.org/schema/kernel-4 http://schema.datacite.org/meta/kernel-4/metadata.xsd">
             <!-- Roots of the metadata -->
             <xsl:apply-templates select="root/links"/>
 
-                <alternateIdentifiers>
-                    <xsl:apply-templates select="root/identifier"/>
+            <alternateIdentifiers>
+                <xsl:apply-templates select="root/identifier"/>
                 <xsl:apply-templates select="root/id"/>
                 <xsl:apply-templates select="root/zbmath_url"/>
-                </alternateIdentifiers>
+            </alternateIdentifiers>
             <creators>
                 <xsl:apply-templates select="root/contributors/authors"/>
             </creators>
 
-                <descriptions>
+            <descriptions>
                 <xsl:apply-templates select="root/editorial_contributions/text"/>
-                </descriptions>
-                       <xsl:apply-templates select="root/title"/>
-                <xsl:apply-templates select="root/source/series/publisher"/>
-                       <xsl:apply-templates select="root/year"/>
+            </descriptions>
+            <xsl:apply-templates select="root/title"/>
+            <xsl:apply-templates select="root/source/series/publisher"/>
+            <xsl:apply-templates select="root/year"/>
             <subjects>
                 <xsl:apply-templates select="root/msc"/>
                 <xsl:apply-templates select="root/keywords"/>
             </subjects>
-                <xsl:apply-templates select="root/language/languages"/>
-                <xsl:apply-templates select="root/document_type/description"/>
-               <relatedIdentifiers>
+            <xsl:apply-templates select="root/language/languages"/>
+            <xsl:apply-templates select="root/document_type/description"/>
+            <relatedIdentifiers>
                 <xsl:apply-templates select="//references/doi[normalize-space()]"/>
-            <!-- Select all references with empty DOI elements -->
-            <xsl:apply-templates select="//references[doi[not(normalize-space())]]"/>
+                <!-- Select all references with empty DOI elements -->
+                <xsl:apply-templates select="//references[doi[not(normalize-space())]]"/>
             </relatedIdentifiers>
-                <rightsList> <!-- this generates the copyrights and legal aspect wihtin the xslt -->
+            <!-- Wrap the rights element inside a rightsList element -->
+          <rightsList> <!-- this generates the copyrights and legal aspect wihtin the xslt -->
                 <rights xml:lang="en"
                         schemeURI="https://api.zbmath.org/v1/"
                         rightsIdentifierScheme="zbMATH"
@@ -49,275 +50,318 @@ Made by Shiraz Malla Mohamad member of zbmath Team-->
 Content generated by zbMATH Open, such as reviews, classifications, software, or author disambiguation data, are distributed under CC-BY-SA 4.0. This defines the license for the whole dataset, which also contains non-copyrighted bibliographic metadata and reference data derived from I4OC (CC0). Note that the API only provides a subset of the data in the zbMATH Open Web interface. In several cases, third-party information, such as abstracts, cannot be made available under a suitable license through the API. In those cases, we replaced the data with the string
 "zbMATH Open Web Interface contents unavailable due to conflicting licenses."</rights>
             </rightsList>
-              <relatedItems>
-                 <xsl:apply-templates select="root/references" mode="relatedItems"/>
-                  <xsl:apply-templates select="root/source"/>
+            <relatedItems>
+                <xsl:apply-templates select="root/references" mode="relatedItems"/>
+                <xsl:apply-templates select="root/source"/>
             </relatedItems>
-         </resource>
-         </xsl:template>
-<!-- Template for processing identifiers -->
-       <xsl:template match="root/links">
-    <xsl:choose>
-        <!-- Process the first 'links' node that has a 'doi' identifier -->
-        <xsl:when test="self::links[type = 'doi' and normalize-space(identifier) != ''][1]">
-            <identifier identifierType="DOI">
-                <xsl:value-of select="identifier"/>
-            </identifier>
-        </xsl:when>
-        <!-- If no 'doi' identifier is present, consider 'arxiv' -->
-        <xsl:when test="self::links[type = 'arxiv' and normalize-space(identifier) != ''][1] and not(preceding-sibling::links[type = 'doi' and normalize-space(identifier) != ''])">
-            <identifier identifierType="ARXIV">
-                <xsl:value-of select="identifier"/>
-            </identifier>
-        </xsl:when>
-    </xsl:choose>
-</xsl:template>
-<!-- Template for processing the rest of the  identifiers of our Metadata and considered as alternative identifiers-->
-     <xsl:template match="identifier">
-          <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
-        <alternateIdentifier alternateIdentifierType="zbMATH Identifier">
-            <xsl:value-of select="."/>
-        </alternateIdentifier>
-          </xsl:if>
-        </xsl:template>
+        </resource>
+    </xsl:template>
+    <!-- Template for processing identifiers -->
+    <xsl:template match="root/links">
+        <xsl:choose>
+            <!-- Process the first 'links' node that has a 'doi' identifier -->
+            <xsl:when test="self::links[type = 'doi' and normalize-space(identifier) != ''][1]">
+                <identifier identifierType="DOI">
+                    <xsl:value-of select="identifier"/>
+                </identifier>
+            </xsl:when>
+            <!-- If no 'doi' identifier is present, consider 'arxiv' -->
+            <xsl:when
+                    test="self::links[type = 'arxiv' and normalize-space(identifier) != ''][1] and not(preceding-sibling::links[type = 'doi' and normalize-space(identifier) != ''])">
+                <identifier identifierType="ARXIV">
+                    <xsl:value-of select="identifier"/>
+                </identifier>
+            </xsl:when>
+        </xsl:choose>
+    </xsl:template>
+    <!-- Template for processing the rest of the  identifiers of our Metadata and considered as alternative identifiers-->
+    <xsl:template match="identifier">
+        <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
+            <alternateIdentifier alternateIdentifierType="zbMATH Identifier">
+                <xsl:value-of select="."/>
+            </alternateIdentifier>
+        </xsl:if>
+    </xsl:template>
     <xsl:template match="id">
-         <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
-    <alternateIdentifier alternateIdentifierType="zbMATH Document ID">
-        <xsl:value-of select="."/>
-    </alternateIdentifier>
-         </xsl:if>
+        <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
+            <alternateIdentifier alternateIdentifierType="zbMATH Document ID">
+                <xsl:value-of select="."/>
+            </alternateIdentifier>
+        </xsl:if>
     </xsl:template>
-     <xsl:template match="zbmath_url">
-          <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
-        <alternateIdentifier alternateIdentifierType="URL">
-            <xsl:value-of select="."/>
-        </alternateIdentifier>
-          </xsl:if>
+    <xsl:template match="zbmath_url">
+        <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
+            <alternateIdentifier alternateIdentifierType="URL">
+                <xsl:value-of select="."/>
+            </alternateIdentifier>
+        </xsl:if>
     </xsl:template>
 
     <!-- Template for processing authors -->
-  <xsl:template match="authors">
-    <creator>
-        <creatorName nameType="Personal">
-            <xsl:choose>
-                <xsl:when test="normalize-space(name) = '' or name = 'None' or name = 'none'">:unav</xsl:when>
-                <xsl:otherwise>
-                    <xsl:value-of select="normalize-space(name)"/>
-                </xsl:otherwise>
-            </xsl:choose>
-        </creatorName>
+    <xsl:template match="authors">
+        <creator>
+            <creatorName nameType="Personal">
+                <xsl:choose>
+                    <xsl:when test="normalize-space(name) = '' or name = 'None' or name = 'none'">:unav</xsl:when>
+                    <xsl:otherwise>
+                        <xsl:value-of select="normalize-space(name)"/>
+                    </xsl:otherwise>
+                </xsl:choose>
+            </creatorName>
 
-        <givenName>
-            <xsl:choose>
-                <xsl:when test="normalize-space(name) = '' or name = 'None' or name = 'none'">:unav</xsl:when>
-                <xsl:otherwise>
-                    <xsl:value-of select="normalize-space(substring-before(name, ','))"/>
-                </xsl:otherwise>
-            </xsl:choose>
-        </givenName>
+            <givenName>
+                <xsl:choose>
+                    <xsl:when test="normalize-space(name) = '' or name = 'None' or name = 'none'">:unav</xsl:when>
+                    <xsl:otherwise>
+                        <xsl:value-of select="normalize-space(substring-before(name, ','))"/>
+                    </xsl:otherwise>
+                </xsl:choose>
+            </givenName>
 
-        <familyName>
-            <xsl:choose>
-                <xsl:when test="normalize-space(name) = '' or name = 'None' or name = 'none'">:unav</xsl:when>
-                <xsl:otherwise>
-                    <xsl:value-of select="normalize-space(substring-after(name, ', '))"/>
-                </xsl:otherwise>
-            </xsl:choose>
-        </familyName>
+            <familyName>
+                <xsl:choose>
+                    <xsl:when test="normalize-space(name) = '' or name = 'None' or name = 'none'">:unav</xsl:when>
+                    <xsl:otherwise>
+                        <xsl:value-of select="normalize-space(substring-after(name, ', '))"/>
+                    </xsl:otherwise>
+                </xsl:choose>
+            </familyName>
 
-        <nameIdentifier schemeURI="https://zbmath.org/" nameIdentifierScheme="zbMATH Author Code">
-            <xsl:choose>
-                <xsl:when test="normalize-space(codes) = '' or codes = 'None' or codes = 'none'">:unav</xsl:when>
-                <xsl:otherwise>
-                    <xsl:value-of select="normalize-space(codes)"/>
-                </xsl:otherwise>
-            </xsl:choose>
-        </nameIdentifier>
-    </creator>
-</xsl:template>
+            <nameIdentifier schemeURI="https://zbmath.org/" nameIdentifierScheme="zbMATH Author Code">
+                <xsl:choose>
+                    <xsl:when test="normalize-space(codes) = '' or codes = 'None' or codes = 'none'">:unav</xsl:when>
+                    <xsl:otherwise>
+                        <xsl:value-of select="normalize-space(codes)"/>
+                    </xsl:otherwise>
+                </xsl:choose>
+            </nameIdentifier>
+        </creator>
+    </xsl:template>
 
 
     <!-- Template for processing titles -->
     <xsl:template match="title">
-    <titles>
-        <title xml:lang="en">
+        <titles>
+            <title xml:lang="en">
+                <xsl:choose>
+                    <xsl:when test="normalize-space(.) = '' or . = 'None' or . = 'none'">:unkn</xsl:when>
+                    <xsl:otherwise>
+                        <xsl:value-of select="normalize-space(.)"/>
+                    </xsl:otherwise>
+                </xsl:choose>
+            </title>
+        </titles>
+    </xsl:template>
+
+
+    <xsl:template match="publisher">
+        <publisher xml:lang="en">
             <xsl:choose>
-                <xsl:when test="normalize-space(.) = '' or . = 'None' or . = 'none'">:unkn</xsl:when>
+                <xsl:when test="normalize-space(.) = '' or . = 'None' or . = 'none'">:unav</xsl:when>
                 <xsl:otherwise>
-                    <xsl:value-of select="normalize-space(.)"/>
+                    <xsl:value-of select="."/>
                 </xsl:otherwise>
             </xsl:choose>
-        </title>
-    </titles>
-</xsl:template>
-
-
-<xsl:template match="publisher">
-    <publisher xml:lang="en">
-        <xsl:choose>
-            <xsl:when test="normalize-space(.) = '' or . = 'None' or . = 'none'">:unav</xsl:when>
-            <xsl:otherwise>
-                <xsl:value-of select="."/>
-            </xsl:otherwise>
-        </xsl:choose>
-    </publisher>
-</xsl:template>
+        </publisher>
+    </xsl:template>
 
-<xsl:template match="year">
-    <publicationYear>
-        <xsl:choose>
-            <xsl:when test="normalize-space(.) = '' or . = 'None' or . = 'none'">:unav</xsl:when>
-            <xsl:otherwise>
-                <xsl:value-of select="."/>
-            </xsl:otherwise>
-        </xsl:choose>
-    </publicationYear>
-</xsl:template>
+    <xsl:template match="year">
+        <publicationYear>
+            <xsl:choose>
+                <xsl:when test="normalize-space(.) = '' or . = 'None' or . = 'none'">:unav</xsl:when>
+                <xsl:otherwise>
+                    <xsl:value-of select="."/>
+                </xsl:otherwise>
+            </xsl:choose>
+        </publicationYear>
+    </xsl:template>
 
 
     <!-- Template for processing the language of the document -->
-      <xsl:template match="languages">
-           <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
+    <xsl:template match="languages">
+        <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
             <language>
-             <xsl:value-of select="."/>
+                <xsl:value-of select="."/>
             </language>
-           </xsl:if>
-            </xsl:template>
+        </xsl:if>
+    </xsl:template>
     <!-- Template for processing  the document type which can be various and needs to be properly handeld -->
     <xsl:template match="description">
-    <resourceType>
-        <xsl:choose>
-            <xsl:when test="contains(translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz'), 'article')">
-                <xsl:attribute name="resourceTypeGeneral">JournalArticle</xsl:attribute>
-            </xsl:when>
-            <xsl:when test="contains(translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz'), 'book')">
-                <xsl:attribute name="resourceTypeGeneral">Book</xsl:attribute>
-            </xsl:when>
-            <xsl:otherwise>
-                <xsl:attribute name="resourceTypeGeneral">Other</xsl:attribute>
-            </xsl:otherwise>
-        </xsl:choose>
-        <xsl:value-of select="."/>
-    </resourceType>
-</xsl:template>
-     <!-- Template for processing source as relatedItem -->
+        <resourceType>
+            <xsl:choose>
+                <xsl:when
+                        test="contains(translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz'), 'article')">
+                    <xsl:attribute name="resourceTypeGeneral">JournalArticle</xsl:attribute>
+                </xsl:when>
+                <xsl:when
+                        test="contains(translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz'), 'book')">
+                    <xsl:attribute name="resourceTypeGeneral">Book</xsl:attribute>
+                </xsl:when>
+                <xsl:otherwise>
+                    <xsl:attribute name="resourceTypeGeneral">Other</xsl:attribute>
+                </xsl:otherwise>
+            </xsl:choose>
+            <xsl:value-of select="."/>
+        </resourceType>
+    </xsl:template>
+    <!-- Template for processing source as relatedItem -->
     <xsl:template match="source">
-         <relatedItem relationType="IsPublishedIn" relatedItemType="Book">
-        <!-- Select ISSN with type 'print' -->
-        <relatedItemIdentifier relatedItemIdentifierType="ISSN">
-            <xsl:value-of select="descendant::issn[type='print']/number"/>
-        </relatedItemIdentifier>
+        <relatedItem relationType="IsPublishedIn" relatedItemType="Book">
+            <!-- Select ISSN with type 'print' -->
+            <relatedItemIdentifier relatedItemIdentifierType="ISSN">
+                <xsl:value-of select="descendant::issn[type='print']/number"/>
+            </relatedItemIdentifier>
             <!-- Process title -->
             <titles>
                 <title>
-                    <xsl:value-of select="series/title"/>
+                    <xsl:choose>
+                        <xsl:when
+                                test="normalize-space(series/title) = '' or series/title = 'None' or series/title = 'none'">
+                            <xsl:text>:unav</xsl:text>
+                        </xsl:when>
+                        <xsl:otherwise>
+                            <xsl:value-of select="series/title"/>
+                        </xsl:otherwise>
+                    </xsl:choose>
                 </title>
             </titles>
-              <publicationYear>
-                <xsl:value-of select="series/year"/>
+            <publicationYear>
+                <xsl:choose>
+                    <xsl:when test="normalize-space(series/year) = '' or series/year = 'None' or series/year = 'none'">
+                        <xsl:text>:unav</xsl:text>
+                    </xsl:when>
+                    <xsl:otherwise>
+                        <xsl:value-of select="series/year"/>
+                    </xsl:otherwise>
+                </xsl:choose>
             </publicationYear>
 
 
             <!-- Process publication year -->
 
-            <!-- Process volume -->
-            <volume>
-                <xsl:value-of select="series/volume"/>
-            </volume>
-            <!-- Process issue -->
-            <issue>
-                <xsl:value-of select="series/issue"/>
-            </issue>
-            <!-- Process pages  start with first page and end with last page -->
+            <xsl:if test="normalize-space(series/volume) != '' and series/volume != 'None' and series/volume != 'none'">
+                <volume>
+                    <xsl:value-of select="series/volume"/>
+                </volume>
+            </xsl:if>
+
+            <xsl:if test="normalize-space(series/issue) != '' and series/issue != 'None' and series/issue != 'none'">
+                <issue>
+                    <xsl:value-of select="series/issue"/>
+                </issue>
+            </xsl:if>
+
             <xsl:variable name="pagesText" select="normalize-space(pages)"/>
             <xsl:variable name="firstPage" select="substring-before($pagesText, '-')"/>
             <xsl:variable name="lastPage" select="substring-after($pagesText, '-')"/>
-            <firstPage>
-                <xsl:value-of select="$firstPage"/>
-            </firstPage>
-            <lastPage>
-                <xsl:value-of select="$lastPage"/>
-            </lastPage>
-              <!-- Process publisher -->
-              <publisher>
-                <xsl:value-of select="series/publisher"/>
+
+            <xsl:if test="normalize-space($firstPage) != '' and $firstPage != 'None' and $firstPage != 'none'">
+                <firstPage>
+                    <xsl:value-of select="$firstPage"/>
+                </firstPage>
+            </xsl:if>
+
+            <xsl:if test="normalize-space($lastPage) != '' and $lastPage != 'None' and $lastPage != 'none'">
+                <lastPage>
+                    <xsl:value-of select="$lastPage"/>
+                </lastPage>
+            </xsl:if>
+            <!-- Process publisher -->
+            <publisher>
+                <xsl:choose>
+                    <xsl:when
+                            test="normalize-space(series/publisher) = '' or series/publisher = 'None' or series/publisher = 'none'">
+                        <xsl:text>:unav</xsl:text>
+                    </xsl:when>
+                    <xsl:otherwise>
+                        <xsl:value-of select="series/publisher"/>
+                    </xsl:otherwise>
+                </xsl:choose>
             </publisher>
         </relatedItem>
     </xsl:template>
 
-<!-- Template for processing text node into description text with its subproperty -->
-        <xsl:template match="text">
-            <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
-        <description xml:lang="en" descriptionType="Abstract">
+    <!-- Template for processing text node into description text with its subproperty -->
+    <xsl:template match="text">
+        <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
+            <description xml:lang="en" descriptionType="Abstract">
 
-         <xsl:value-of select="normalize-space(.)"/>
+                <xsl:value-of select="normalize-space(.)"/>
 
-        </description>
-            </xsl:if>
-        </xsl:template>
-     <!-- Template for processing MSC  (Mathematics Subject Classification)
-      transforming all its values -->
+            </description>
+        </xsl:if>
+    </xsl:template>
+    <!-- Template for processing MSC  (Mathematics Subject Classification)
+     transforming all its values -->
     <xsl:template match="msc">
-         <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
-    <subject>
-        <xsl:attribute name="subjectScheme">
-            <xsl:value-of select="scheme"/>
-        </xsl:attribute>
-        <xsl:attribute name="classificationCode">
-            <xsl:value-of select="code"/>
-        </xsl:attribute>
-        <xsl:value-of select="text"/>
-    </subject>
-         </xsl:if>
-</xsl:template>
-
-
-       <xsl:template match="keywords">
-            <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
-
-        <subject subjectScheme="keyword">
-            <xsl:value-of select="."/>
-        </subject>
-            </xsl:if>
-        </xsl:template>
+        <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
+            <subject>
+                <xsl:attribute name="subjectScheme">
+                    <xsl:value-of select="scheme"/>
+                </xsl:attribute>
+                <xsl:attribute name="classificationCode">
+                    <xsl:value-of select="code"/>
+                </xsl:attribute>
+                <xsl:value-of select="text"/>
+            </subject>
+        </xsl:if>
+    </xsl:template>
+
 
+    <xsl:template match="keywords">
+        <xsl:if test="normalize-space(.) != '' and . != 'None'and . != 'none'">
 
-  <xsl:template match="doi[normalize-space()]">
-        <relatedIdentifier relatedIdentifierType="DOI" relationType="Cites" resourceTypeGeneral="JournalArticle"><xsl:value-of select="normalize-space(.)"/></relatedIdentifier>
+            <subject subjectScheme="keyword">
+                <xsl:value-of select="."/>
+            </subject>
+        </xsl:if>
     </xsl:template>
 
 
-    <xsl:template match="references[not(doi[normalize-space()])]">
-        <relatedIdentifier relatedIdentifierType="URL" relationType="IsCitedBy"><xsl:value-of select="concat('https://zbmath.org/', zbmath/document_id)"/></relatedIdentifier>
+    <xsl:template match="doi[normalize-space()]">
+        <relatedIdentifier relatedIdentifierType="DOI" relationType="Cites" resourceTypeGeneral="JournalArticle">
+            <xsl:value-of select="normalize-space(.)"/>
+        </relatedIdentifier>
     </xsl:template>
 
 
+    <xsl:template match="references[not(doi[normalize-space()])]">
+        <relatedIdentifier relatedIdentifierType="URL" relationType="IsCitedBy">
+            <xsl:value-of select="concat('https://zbmath.org/', zbmath/document_id)"/>
+        </relatedIdentifier>
+    </xsl:template>
 
 
-  <!-- Template to match references and transform into relatedItems
-each reference has its own relatedItem node and all of its values goes under this node -->
-  <xsl:template match="references" mode="relatedItems">
+    <!-- Template to match references and transform into relatedItems
+  each reference has its own relatedItem node and all of its values goes under this node -->
+    <xsl:template match="references" mode="relatedItems">
         <relatedItem relatedItemType="JournalArticle" relationType="Cites">
-              <!-- the relatedItemIdentifier should have the same value of identifier as they are in the relatedIdentifiers -->
-             <relatedItemIdentifier>
-    <xsl:choose>
-        <xsl:when test="doi[normalize-space()]">
-            <xsl:attribute name="relatedItemIdentifierType">DOI</xsl:attribute>
-            <xsl:value-of select="doi"/>
-        </xsl:when>
-        <xsl:otherwise>
-            <xsl:attribute name="relatedItemIdentifierType">URL</xsl:attribute>
-            <xsl:value-of select="concat('https://zbmath.org/', zbmath/document_id)"/>
-        </xsl:otherwise>
-    </xsl:choose>
-</relatedItemIdentifier>
+            <!-- the relatedItemIdentifier should have the same value of identifier as they are in the relatedIdentifiers -->
+            <relatedItemIdentifier>
+                <xsl:choose>
+                    <xsl:when test="doi[normalize-space()]">
+                        <xsl:attribute name="relatedItemIdentifierType">DOI</xsl:attribute>
+                        <xsl:value-of select="doi"/>
+                    </xsl:when>
+                    <xsl:otherwise>
+                        <xsl:attribute name="relatedItemIdentifierType">URL</xsl:attribute>
+                        <xsl:value-of select="concat('https://zbmath.org/', zbmath/document_id)"/>
+                    </xsl:otherwise>
+                </xsl:choose>
+            </relatedItemIdentifier>
             <creators>
                 <xsl:for-each select="zbmath/author_codes">
                     <creator>
-                         <creatorName nameType="Personal">
-                <xsl:choose>
-                    <xsl:when test="contains(translate(substring-after(., '.'), '0123456789.', ''), '-')">
-                        <xsl:value-of select="concat(
+                        <creatorName nameType="Personal">
+                            <xsl:choose>
+                                <xsl:when test="normalize-space(.) = '' or . = 'None' or . = 'none'">
+                                    <xsl:text>:unav</xsl:text>
+                                </xsl:when>
+                                <xsl:otherwise>
+                                    <xsl:choose>
+                                        <xsl:when
+                                                test="contains(translate(substring-after(., '.'), '0123456789.', ''), '-')">
+                                            <xsl:value-of select="concat(
                             translate(substring(translate(substring-before(., '.'), '0123456789.', ''), 1, 1), 'abcdefghijklmnopqrstuvwxyz', 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'),
                             substring(translate(substring-before(., '.'), '0123456789.', ''), 2),
                             ', ',
@@ -327,84 +371,114 @@ each reference has its own relatedItem node and all of its values goes under thi
                                     substring(translate(substring-after(., '.'), '0123456789.', ''), 2)
                                 ), '-')
                         )"/>
-                    </xsl:when>
-                    <xsl:otherwise>
-                        <xsl:value-of select="concat(
+                                        </xsl:when>
+                                        <xsl:otherwise>
+                                            <xsl:value-of select="concat(
                             translate(substring(translate(substring-before(., '.'), '0123456789.', ''), 1, 1), 'abcdefghijklmnopqrstuvwxyz', 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'),
                             substring(translate(substring-before(., '.'), '0123456789.', ''), 2),
                             ', ',
                             translate(substring(translate(substring-after(., '.'), '0123456789.', ''), 1, 1), 'abcdefghijklmnopqrstuvwxyz', 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'),
                             substring(translate(substring-after(., '.'), '0123456789.', ''), 2)
                         )"/>
-                    </xsl:otherwise>
-                </xsl:choose>
-            </creatorName>
+                                        </xsl:otherwise>
+                                    </xsl:choose>
+                                </xsl:otherwise>
+                            </xsl:choose>
+                        </creatorName>
                         <givenName>
                             <xsl:choose>
-                                <xsl:when test="contains(translate(substring-after(., '.'), '0123456789.', ''), '-')">
-                                    <xsl:value-of select="substring-before(
+                                <xsl:when test="normalize-space(.) = '' or . = 'None' or . = 'none'">
+                                    <xsl:text>:unav</xsl:text>
+                                </xsl:when>
+                                <xsl:otherwise>
+                                    <xsl:choose>
+                                        <xsl:when
+                                                test="contains(translate(substring-after(., '.'), '0123456789.', ''), '-')">
+                                            <xsl:value-of select="substring-before(
                                         concat(
                                             translate(substring(translate(substring-after(., '.'), '0123456789.', ''), 1, 1), 'abcdefghijklmnopqrstuvwxyz', 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'),
                                             substring(translate(substring-after(., '.'), '0123456789.', ''), 2)
                                         ), '-')"/>
-                                </xsl:when>
-                                <xsl:otherwise>
-                                    <xsl:value-of select="concat(
+                                        </xsl:when>
+                                        <xsl:otherwise>
+                                            <xsl:value-of select="concat(
                                         translate(substring(translate(substring-after(., '.'), '0123456789.', ''), 1, 1), 'abcdefghijklmnopqrstuvwxyz', 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'),
                                         substring(translate(substring-after(., '.'), '0123456789.', ''), 2)
                                     )"/>
+                                        </xsl:otherwise>
+                                    </xsl:choose>
                                 </xsl:otherwise>
                             </xsl:choose>
                         </givenName>
                         <familyName>
-                            <xsl:value-of select="concat(
+                            <xsl:choose>
+                                <xsl:when test="normalize-space(.) = '' or . = 'None' or . = 'none'">
+                                    <xsl:text>:unav</xsl:text>
+                                </xsl:when>
+                                <xsl:otherwise>
+                                    <xsl:value-of select="concat(
                                 translate(substring(translate(substring-before(., '.'), '0123456789.', ''), 1, 1), 'abcdefghijklmnopqrstuvwxyz', 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'),
                                 substring(translate(substring-before(., '.'), '0123456789.', ''), 2)
                             )"/>
+                                </xsl:otherwise>
+                            </xsl:choose>
                         </familyName>
                     </creator>
                 </xsl:for-each>
             </creators>
-           <titles>
-            <xsl:choose>
-                <xsl:when test="contains(text, &quot;''&quot;)">
-                    <!-- Extract text between quotes -->
-                   <title>
-                        <xsl:variable name="text" select="text"/>
-                        <xsl:variable name="title-text" select="substring-before(substring-after($text, &quot;''&quot;), &quot;''&quot;)"/>
-                        <!-- Remove digits and trailing punctuation -->
-                        <xsl:variable name="title-no-digits" select="translate($title-text, '0123456789', '')"/>
-                        <xsl:value-of select="normalize-space(
+            <titles>
+                <xsl:choose>
+                    <xsl:when test="normalize-space(text) = '' or text = 'None' or text = 'none'">
+                        <title>:unav</title>
+                    </xsl:when>
+                    <xsl:when test="contains(text, &quot;''&quot;)">
+                        <!-- Extract text between quotes -->
+                        <title>
+                            <xsl:variable name="text" select="text"/>
+                            <xsl:variable name="title-text"
+                                          select="substring-before(substring-after($text, &quot;''&quot;), &quot;''&quot;)"/>
+                            <!-- Remove digits and trailing punctuation -->
+                            <xsl:variable name="title-no-digits" select="translate($title-text, '0123456789', '')"/>
+                            <xsl:value-of select="normalize-space(
                             translate(
                                 $title-no-digits,
                                 ',.',
                                 ''
                             )
                         )"/>
-                    </title>
-                </xsl:when>
-                <xsl:otherwise>
-                    <!-- Extract text after the first comma and before the last comma, excluding digits and removing trailing commas/periods -->
-                    <title>
-                        <xsl:variable name="text" select="text"/>
-                        <xsl:variable name="text-no-digits" select="translate($text, '0123456789', '')"/>
-                        <xsl:variable name="first-comma" select="substring-after($text-no-digits, ',')"/>
-                        <xsl:variable name="last-part" select="substring-before($text-no-digits, substring-after($text-no-digits, ', '))"/>
-                        <xsl:variable name="last-comma" select="substring-before($last-part, ',')"/>
-                        <xsl:variable name="result-text" select="normalize-space(concat(substring-before($first-comma, substring-after($first-comma, ', ')), substring-after($first-comma, ', ')))"/>
-                        <xsl:value-of select="normalize-space(
+                        </title>
+                    </xsl:when>
+                    <xsl:otherwise>
+                        <!-- Extract text after the first comma and before the last comma, excluding digits and removing trailing commas/periods -->
+                        <title>
+                            <xsl:variable name="text" select="text"/>
+                            <xsl:variable name="text-no-digits" select="translate($text, '0123456789', '')"/>
+                            <xsl:variable name="first-comma" select="substring-after($text-no-digits, ',')"/>
+                            <xsl:variable name="last-part"
+                                          select="substring-before($text-no-digits, substring-after($text-no-digits, ', '))"/>
+                            <xsl:variable name="last-comma" select="substring-before($last-part, ',')"/>
+                            <xsl:variable name="result-text"
+                                          select="normalize-space(concat(substring-before($first-comma, substring-after($first-comma, ', ')), substring-after($first-comma, ', ')))"/>
+                            <xsl:value-of select="normalize-space(
                             translate(
                                 $result-text,
                                 ',.',
                                 ''
                             )
                         )"/>
-                    </title>
-                </xsl:otherwise>
-            </xsl:choose>
-        </titles>
+                        </title>
+                    </xsl:otherwise>
+                </xsl:choose>
+            </titles>
             <publicationYear>
-                <xsl:value-of select="zbmath/year"/>
+                <xsl:choose>
+                    <xsl:when test="normalize-space(zbmath/year) = '' or zbmath/year = 'None' or zbmath/year = 'none'">
+                        <xsl:text>:unav</xsl:text>
+                    </xsl:when>
+                    <xsl:otherwise>
+                        <xsl:value-of select="zbmath/year"/>
+                    </xsl:otherwise>
+                </xsl:choose>
             </publicationYear>
         </relatedItem>
     </xsl:template>