D. Cosley, S. Lam, I. Albert, J. Konstan, and J. Riedl. CHI '03: Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, page 585--592. New York, NY, USA, ACM, (2003)
E. Breck, Y. Choi, and C. Cardie. IJCAI'07: Proceedings of the 20th International Joint Conference on Artifical Intelligence, page 2683--2688. San Francisco, CA, USA, Morgan Kaufmann Publishers Inc., (2007)