diff --git a/references.bib b/references.bib
index bb0d78c..b027e48 100644
--- a/references.bib
+++ b/references.bib
@@ -3386,3 +3386,33 @@ @inproceedings{zeleti2014
   doi       = {10.1007/978-3-662-44745-1_50},
   address   = {Berlin, Heidelberg}
 }
+
+@article{Cobo2011AnAF,
+  title={An approach for detecting, quantifying, and visualizing the evolution of a research field: A practical application to the Fuzzy Sets Theory field},
+  author={M.J. Cobo and Antonio Gabriel L{\'o}pez-Herrera and Enrique Herrera-Viedma and Francisco Herrera},
+  journal={J. Informetrics},
+  year={2011},
+  volume={5},
+  pages={146-166},
+  url={https://api.semanticscholar.org/CorpusID:9814348}
+}
+
+@article{Waltman2012ANM,
+  title={A new methodology for constructing a publication-level classification system of science},
+  author={Ludo Waltman and Nees Jan van Eck},
+  journal={J. Assoc. Inf. Sci. Technol.},
+  year={2012},
+  volume={63},
+  pages={2378-2392},
+  url={https://api.semanticscholar.org/CorpusID:15589099}
+}
+
+@article{Yan2014ResearchDM,
+  title={Research dynamics: Measuring the continuity and popularity of research topics},
+  author={Erjia Yan},
+  journal={J. Informetrics},
+  year={2014},
+  volume={8},
+  pages={98-110},
+  url={https://api.semanticscholar.org/CorpusID:35965754}
+}