M. Collins, and N. Duffy. Advances in Neural Information Processing Systems 14 --- Proceedings of the 2001 Neural Information Processing Systems Conference (NIPS 2001), December 3-8, 2001, Vancouver, British Columbia, Canada, page 625--632. MIT Press, Cambridge, MA, USA, (2002)
M. Collins. Proceedings of the ACL-02 conference on Empirical methods in natural language processing - Volume 10, page 1--8. Stroudsburg, PA, USA, Association for Computational Linguistics, (2002)