diff --git a/01_Topic/topic.bib b/01_Topic/topic.bib
index 18ba411..6dc2759 100644
--- a/01_Topic/topic.bib
+++ b/01_Topic/topic.bib
@@ -784,7 +784,7 @@ OCLC: 935904837}
   year = {2020},
   keywords = {Analytical hierarchy process,Decision-making,Multi-criteria group recommender systems,Recommendation mechanism},
   pages = {75-84},
-  file = {C\:\\Users\\Hannes.Kuchelmeister\\Zotero\\storage\\EFVTG9VE\\Choudhary_Bharadwaj_2020_Multi-criteria Group Recommender System Based on Analytical Hierarchy Process.pdf}
+  file = {C\:\\Users\\Hannes.Kuchelmeister\\Zotero\\storage\\EFVTG9VE\\Choudhary_Bharadwaj_2020_Multi-criteria Group Recommender System Based on Analytical Hierarchy Process.pdf;C\:\\Users\\Hannes.Kuchelmeister\\Zotero\\storage\\GCKZA5ZN\\2018_MA_Rubinshteyn_Hybrider Recommender für die Produktkonfiguration.pdf}
 }
 
 @incollection{choudharyMulticriteriaGroupRecommender2020a,
@@ -945,4 +945,16 @@ OCLC: 935904837}
   doi = {10.1007/978-3-540-72079-9_20}
 }
 
+@phdthesis{rubinshteynEntwicklungHybridenRecommender2018,
+  address = {{Karlsruhe}},
+  type = {{Master's thesis}},
+  title = {{Entwicklung eines hybriden Recommender Systems f{\"u}r die Produktkonfiguration}},
+  language = {de},
+  school = {Karlsruhe Institute of Technology},
+  author = {Rubinshteyn, Alexander},
+  month = nov,
+  year = {2018},
+  file = {C\:\\Users\\Hannes.Kuchelmeister\\Zotero\\storage\\JXXN9BU8\\Rubinshteyn - Entwicklung eines hybriden Recommender Systems für.pdf}
+}
+
 
diff --git a/02_Proposal/proposal.bib b/02_Proposal/proposal.bib
index 18ba411..6dc2759 100644
--- a/02_Proposal/proposal.bib
+++ b/02_Proposal/proposal.bib
@@ -784,7 +784,7 @@ OCLC: 935904837}
   year = {2020},
   keywords = {Analytical hierarchy process,Decision-making,Multi-criteria group recommender systems,Recommendation mechanism},
   pages = {75-84},
-  file = {C\:\\Users\\Hannes.Kuchelmeister\\Zotero\\storage\\EFVTG9VE\\Choudhary_Bharadwaj_2020_Multi-criteria Group Recommender System Based on Analytical Hierarchy Process.pdf}
+  file = {C\:\\Users\\Hannes.Kuchelmeister\\Zotero\\storage\\EFVTG9VE\\Choudhary_Bharadwaj_2020_Multi-criteria Group Recommender System Based on Analytical Hierarchy Process.pdf;C\:\\Users\\Hannes.Kuchelmeister\\Zotero\\storage\\GCKZA5ZN\\2018_MA_Rubinshteyn_Hybrider Recommender für die Produktkonfiguration.pdf}
 }
 
 @incollection{choudharyMulticriteriaGroupRecommender2020a,
@@ -945,4 +945,16 @@ OCLC: 935904837}
   doi = {10.1007/978-3-540-72079-9_20}
 }
 
+@phdthesis{rubinshteynEntwicklungHybridenRecommender2018,
+  address = {{Karlsruhe}},
+  type = {{Master's thesis}},
+  title = {{Entwicklung eines hybriden Recommender Systems f{\"u}r die Produktkonfiguration}},
+  language = {de},
+  school = {Karlsruhe Institute of Technology},
+  author = {Rubinshteyn, Alexander},
+  month = nov,
+  year = {2018},
+  file = {C\:\\Users\\Hannes.Kuchelmeister\\Zotero\\storage\\JXXN9BU8\\Rubinshteyn - Entwicklung eines hybriden Recommender Systems für.pdf}
+}
+
 
diff --git a/02_Proposal/sections/20_related_work.tex b/02_Proposal/sections/20_related_work.tex
index 8e11e54..b5b1444 100644
--- a/02_Proposal/sections/20_related_work.tex
+++ b/02_Proposal/sections/20_related_work.tex
@@ -4,4 +4,19 @@
 \section{Group-Based Configuration}
 \label{sec:Related_Work:GroupBasedConfiguration}
 
-One thesis done at CAS Software built a collaborative configurator based on the CAS Merlin Configurator. Here groups of people are able to simultaneously configure a product. If there are any conflicts a conflict resolution process is started. However the prototype only allows a majority voting approach and does not provide any group decision support \cite{raabKollaborativeProduktkonfigurationEchtzeit2019}.
\ No newline at end of file
+In his thesis \citeauthor{raabKollaborativeProduktkonfigurationEchtzeit2019} built a collaborative configurator based on the CAS Merlin Configurator. Here groups of people are able to simultaneously configure a product. If there are any conflicts a conflict resolution process is started. However the prototype only allows a majority voting approach and does not provide any group decision support \cite{raabKollaborativeProduktkonfigurationEchtzeit2019}.
+
+\section{Recommender Systems for Configuration}
+\label{sec:Related_Work:RecommenderSystemsForGonfiguration}
+
+\citeauthor{rubinshteynEntwicklungHybridenRecommender2018} looks at different approaches to recommendation and implements a prototype with CAS Merlin Configurator which uses a hybrid recommender system. His prototype combines constraint-based filtering with collaborative filtering \cite{rubinshteynEntwicklungHybridenRecommender2018}.
+
+
+\todo[inline]{other related work at CAS}
+
+\cite{benzMoeglichkeitenIntelligenterEmpfehlungssysteme2017}
+\cite{ullmannEntwurfUndUmsetzung2017}
+\cite{wetzelPersonalisierterUndLernender2017}
+
+
+\todo[inline]{other related work}
\ No newline at end of file