R. Guha, R. Kumar, P. Raghavan, and A. Tomkins. WWW '04: Proceedings of the 13th international conference on World Wide Web, page 403--412. New York, NY, USA, ACM, (2004)
R. Guha, R. McCool, and E. Miller. WWW '03: Proceedings of the 12th international conference on World
Wide Web, page 700--709. New York, NY, USA, ACM Press, (2003)