X. Liu, and W. Croft. Proceedings of the 27th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, page 186--193. New York, NY, USA, ACM, (2004)
X. Liu, and W. Croft. Proceedings of the 27th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, page 186--193. New York, NY, USA, ACM, (2004)