M. Hu, and B. Liu. Proceedings of the tenth ACM SIGKDD international conference on Knowledge discovery and data mining, page 168--177. New York, NY, USA, ACM, (2004)
M. Claypool, P. Le, M. Wased, and D. Brown. Proceedings of the 6th international conference on Intelligent user interfaces, page 33--40. New York, NY, USA, ACM, (2001)