Y. Chan, and H. Ng. Proceedings of the 45th Annual Meeting of the Association of Computational Linguistics, page 49--56. Prague, Czech Republic, Association for Computational Linguistics, (June 2007)
H. Nguyen, and A. Smeulders. ICML '04: Proceedings of the twenty-first international conference on Machine learning, page 79. New York, NY, USA, ACM Press, (2004)
M. Tang, X. Luo, and S. Roukos. ACL '02: Proceedings of the 40th Annual Meeting on Association for Computational Linguistics, page 120--127. Morristown, NJ, USA, Association for Computational Linguistics, (2001)