J. Weeds, D. Weir, и D. McCarthy. Proceedings of the 20th international conference on Computational Linguistics, стр. 1015. Association for Computational Linguistics, (2004)
E. Gabrilovich, и S. Markovitch. Proceedings of the 20th international joint conference on artificial intelligence, 6, стр. 12. Morgan Kaufmann Publishers Inc., (2007)