diff --git a/common/refs.bib b/common/refs.bib
index ded02f9..bd4e349 100644
--- a/common/refs.bib
+++ b/common/refs.bib
@@ -87,3 +87,14 @@
   publisher={ACM}
 }
 
+@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={IEEE transactions on pattern analysis and machine intelligence},
+  volume={26},
+  number={10},
+  pages={1367--1372},
+  year={2004},
+  publisher={IEEE}
+}
+
diff --git a/report/report.tex b/report/report.tex
index 93cb1a1..266f123 100644
--- a/report/report.tex
+++ b/report/report.tex
@@ -408,8 +408,20 @@ and an isomorphism has been found; if not, we move on to the next permutation.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \section{Pattern-match}
+
 \todo{}
 
+\subsection{Ullmann's algorithm}
+
+One of the classical algorithms to deal with the subgraph isomorphism problem
+was first described by Julian R Ullmann in 1976~\cite{ullmann1976algorithm}.
+Another, more recent algorithm to deal with this problem is Luigi P Cordella's
+VF2 algorithm~\cite{cordella2004sub}, published in 2004. This algorithm is
+mostly Ullmann's algorithm, transcribed in a recursive writing, with the
+addition of five heuristics. \qtodo{Why not use it then?}
+
+\todo{Describe Ullmann}
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \section{Performance}