C. Saunders, D. Hardoon, J. Shawe-Taylor, and G. Widmer. Machine Learning: ECML 2004, 15th European Conference on, volume 3201 of Lecture Notes in Computer Science, page 384-395. Springer, (2004)
Q. Zhao, S. Hoi, T. Liu, S. Bhowmick, M. Lyu, and W. Ma. WWW '06: Proceedings of the 15th international conference on World Wide Web, page 543--552. New York, NY, USA, ACM Press, (2006)