D. Gruhl, R. Guha, D. Liben-Nowell, и A. Tomkins. WWW '04: Proceedings of the 13th international conference on World Wide Web, стр. 491--501. New York, NY, USA, ACM Press, (2004)
C. Brooks, и N. Montanez. WWW '06: Proceedings of the 15th international conference on World Wide Web, стр. 625-632. New York, NY, USA, ACM Press, (2006)