X. Liu, and W. Croft. ECIR'08: Proceedings of the IR research, 30th European conference on Advances in information retrieval, page 454--462. Berlin, Heidelberg, Springer-Verlag, (2008)
X. Liu, and W. Croft. SIGIR '04: 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)
G. Erkan. Proceedings of the main conference on Human Language Technology Conference of the North American Chapter of the Association of Computational Linguistics, page 479--486. Morristown, NJ, USA, Association for Computational Linguistics, (2006)