diff --git a/02_Proposal/sections/10_foundations.tex b/02_Proposal/sections/10_foundations.tex
index db87e93..8097967 100644
--- a/02_Proposal/sections/10_foundations.tex
+++ b/02_Proposal/sections/10_foundations.tex
@@ -4,10 +4,13 @@
 \section{Recommender System}
 \label{Foundations:RecommenderSystem}
 
+A recommender system is a system that gives individualized recommendations to users to guide them through a large space of objects \cite[~ p. 331]{burkeHybridRecommenderSystems}.
+
+
 \section{Product Configuration}
 \label{Foundations:ProductConfiguration}
 
-Product configuration is a process consisting of a series of decision tasks whereby a product is constructed of components which interact with each other. During a configuration process no new components are created. Their interplay and specification is defined beforehand \cite[~ p. 42-43]{sabinProductConfigurationFrameworksa1998}.
+Product configuration is a process consisting of a series of decision tasks whereby a product is constructed of components which interact with each other. During a configuration process no new components are created. Their interplay and specification is defined beforehand \cite[~ p. 42, 43]{sabinProductConfigurationFrameworksa1998}.
 
 Formally a configuration problem can be specified as a \emph{constraint satisfaction problem (CSP)} \cite{tsangFoundationsConstraintSatisfaction1993} as 
 \[