S. McNee, N. Kapoor, und J. Konstan. Proceedings of the 2006 20th anniversary conference on Computer supported cooperative work, Seite 171--180. New York, NY, USA, ACM, (2006)
R. Jäschke, F. Eisterlehner, A. Hotho, und G. Stumme. RecSys '09: Proceedings of the 2009 ACM Conference on Recommender Systems, New York, NY, USA, ACM, (2009)(to appear).