M. Simkin, and V. Roychowdury. Journal of the American Society for Information Science & Technology, 58 (11):
1661-1673(September 2007)IL: 3 charts, 1 diagram, 2 graphs.
J. Wermter, and U. Hahn. 44th Annual Meeting of the Association for Computational Linguistics, page 785--792. Sydney, Australia, Association for Computational Linguistics, (July 2006)