diff -r a037254714b3 -r 2f479109a71d doc/references.bib
--- a/doc/references.bib	Mon Mar 30 17:42:30 2015 +0200
+++ b/doc/references.bib	Thu May 14 16:07:38 2015 +0200
@@ -354,3 +354,17 @@
   number =       6,
   pages =        {587--612}
 }
+
+@article{cordella2004sub,
+  title =	 {A (sub) graph isomorphism algorithm for matching
+                  large graphs},
+  author =	 {Cordella, Luigi P and Foggia, Pasquale and Sansone,
+                  Carlo and Vento, Mario},
+  journal =	 {Pattern Analysis and Machine Intelligence, IEEE
+                  Transactions on},
+  volume =	 26,
+  number =	 10,
+  pages =	 {1367--1372},
+  year =	 2004,
+  publisher =	 {IEEE}
+}