Index: doc/theses/fangren_yu_MMath/background.tex
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--- doc/theses/fangren_yu_MMath/background.tex	(revision 18a7dcf12cb8d61e7214bb8aab1e4fe441d56c0e)
+++ doc/theses/fangren_yu_MMath/background.tex	(revision 5db913f46e93b12eef193c9ac4a156a1a6b97739)
@@ -1,4 +1,5 @@
 \chapter{Background}
 
+\cite{Melo17} \cite{Odersky01} \cite{Pierce00}
 
 \section{Polymorphism}