L. Wu, L. Yang, N. Yu, und X. Hua. WWW '09: Proceedings of the 18th international conference on World wide web, Seite 361--370. New York, NY, USA, ACM, (2009)
D. Liu, X. Hua, L. Yang, M. Wang, und H. Zhang. Proceedings of the 18th international conference on World wide web, Seite 351--360. New York, NY, USA, ACM, (2009)
B. Sigurbjörnsson, und R. van Zwol. WWW '08: Proceeding of the 17th international conference on World Wide Web, Seite 327--336. New York, NY, USA, ACM, (2008)