diff --git a/25_Outline/outline.tex b/25_Outline/outline.tex
index ef34c60..d58ddbf 100644
--- a/25_Outline/outline.tex
+++ b/25_Outline/outline.tex
@@ -101,7 +101,7 @@ Commonly for content-based recommenders categories based on content are created
 \FloatBarrier
 
 \section{Problem}
-A group of people with different personal preferences wants to buy products with high variability. Making decisions in the group comes with problems as communicating preferences is complicated.
+A group of people with different personal preferences wants to buy products with high variability. Making decisions in the group comes with problems as communicating preferences is complicated. Group dynamics and biases can lead to suboptimal decisions \cite{kerrBiasJudgmentComparing1996}. 
 
 Examples of that are:
 \begin{itemize}