P. Halácsy, A. Kornai, and C. Oravecz. Proceedings of the 45th Annual Meeting of the ACL, page 209--212. Stroudsburg, Association for Computational Linguistics, (2007)
J. Hajic, and B. Hladká. Proceedings of the 17th international conference on Computational linguistics, page 483--490. Association for Computational Linguistics, (1998)