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 Press, (2004)
X. Song, Y. Chi, K. Hino, and B. Tseng. WWW '07: Proceedings of the 16th international conference on World Wide Web, page 191--200. New York, NY, USA, ACM Press, (2007)
M. Cha, A. Mislove, and K. Gummadi. WWW '09: Proceedings of the 18th international conference on World wide web, page 721--730. New York, NY, USA, ACM, (2009)