S. Li, A. Karatzoglou, and C. Gentile. Proceedings of the 39th International ACM SIGIR Conference on Research and Development in Information Retrieval, page 539--548. New York, NY, USA, ACM, (2016)
M. O'Connor, and J. Herlocker. Proceedings of the ACM SIGIR Workshop on Recommender Systems: Algorithms and Evaluation, Berkeley, California, USA, (August 1999)