P. Melville, R. Mooney, and R. Nagarajan. Eighteenth National Conference on Artificial Intelligence, page 187--192. Menlo Park, CA, USA, American Association for Artificial Intelligence, (2002)
J. Gemmell, T. Schimoler, B. Mobasher, and R. Burke. Proceedings of the 19th ACM international conference on Information and knowledge management, page 829--838. New York, NY, USA, ACM, (2010)