T. Lavergne, O. Cappé, and F. Yvon. Proceedings the 48th Annual Meeting of the Association for Computational Linguistics, page 504--513. Stroudsburg, Association for Computational Linguistics, (2010)
D. Lin. Proceedings of the 17th international conference on Computational linguistics, page 768--774. Morristown, NJ, USA, Association for Computational Linguistics, (1998)