L. Ding, L. Zhou, T. Finin, and A. Joshi. System Sciences, 2005. HICSS '05. Proceedings of the 38th Annual Hawaii International Conference on, (January 2005)
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)