K. Punera, and S. Merugu. Proceedings of the 19th ACM international conference on Information and knowledge management, page 989--998. New York, NY, USA, ACM, (2010)
G. Dupret, and C. Liao. Proceedings of the third ACM international conference on Web search and data mining, page 181--190. New York, NY, USA, ACM, (2010)