B. Liu, R. Jones, и K. Klinkner. CIKM '06: Proceedings of the 15th ACM international conference on Information and knowledge management, стр. 836--837. New York, NY, USA, ACM Press, (2006)
X. Wang, и C. Zhai. Proceedings of the 30 th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval 2007, (2007)