Index: doc/theses/fangren_yu_MMath/background.tex
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--- doc/theses/fangren_yu_MMath/background.tex	(revision 13887ac2bdbe8d74fb76251860ab3ce811ef25c4)
+++ doc/theses/fangren_yu_MMath/background.tex	(revision 63b32f9d78b543462283bbd288cb90544ee8db78)
@@ -1,4 +1,5 @@
 \chapter{Background}
 
+\cite{Melo17} \cite{Odersky01} \cite{Pierce00}
 
 \section{Polymorphism}