N. Good, J. Schafer, J. Konstan, A. Borchers, B. Sarwar, J. Herlocker, and J. Riedl. AAAI '99/IAAI '99: Proceedings of the sixteenth national conference on Artificial intelligence and the eleventh Innovative applications of artificial intelligence conference innovative applications of artificial intelligence, page 439--446. Menlo Park, CA, USA, American Association for Artificial Intelligence, (1999)
E. Han, and G. Karypis. CIKM '05: Proceedings of the 14th ACM international conference on Information and knowledge management, page 446--452. New York, NY, USA, ACM Press, (2005)
S. Stober, and A. Nürnberger. Knowledge-Based Intelligent Information and Engineering Systems (KES 2006), volume 4251 of LNAI, page 763--770. Berlin / Heidelberg, Springer Verlag, (October 2006)