M. Cafarella, and O. Etzioni. WWW '05: Proceedings of the 14th international conference on World Wide Web, page 442--452. New York, NY, USA, ACM Press, (2005)
J. Cafarella, D. Downey, S. Soderland, and O. Etzioni. Proceedings of Human Language Technology Conference and Conference on Empirical Methods in Natural Language Processing, page 563--570. Association for Computational Linguistics, (2005)