F. Liu, C. Yu, and W. Meng. CIKM '02: Proceedings of the eleventh international conference on Information and knowledge management, page 558--565. New York, NY, USA, ACM Press, (2002)
Z. Dou, R. Song, and J. Wen. WWW '07: Proceedings of the 16th international conference on World Wide Web, page 581--590. New York, NY, USA, ACM Press, (2007)
Y. Xu, K. Wang, B. Zhang, and Z. Chen. WWW '07: Proceedings of the 16th international conference on World Wide Web, page 591--600. New York, NY, USA, ACM Press, (2007)