R. Baeza-Yates, C. Hurtado, und M. Mendoza. Current Trends in Database Technology - EDBT 2004 Workshops, Volume 3268 von Lecture Notes in Computer Science, Springer Berlin Heidelberg, (2005)
R. Kumar, J. Novak, B. Pang, und A. Tomkins. WWW '07: Proceedings of the 16th international conference on World Wide Web, Seite 629--638. New York, NY, USA, ACM, (2007)