L. Hiatt, J. Trafton, A. Harrison, and A. Schulz. Proceedings of the Sixth International Conference on Cognitive Modeling, page 354-355. Pittsburgh, PA, (2004)
M. Johnson, and E. Charniak. Proceedings of 42nd Annual Meeting of the Association for Computational Linguistics (ACL), page 33-39. Barcelona, Spain, (2004)