T. Joachims. Proceedings of the eighth ACM SIGKDD international conference on Knowledge discovery and data mining, page 133--142. New York, NY, USA, ACM, (2002)
K. Wang, T. Walker, and Z. Zheng. KDD '09: Proceedings of the 15th ACM SIGKDD international conference on Knowledge discovery and data mining, page 1355--1364. New York, NY, USA, ACM, (2009)