K. Forbes-Riley, and D. Litman. Proceedings of the main conference on Human Language Technology Conference of the North American Chapter of the Association of Computational Linguistics, page 264--271. Stroudsburg, PA, USA, Association for Computational Linguistics, (2006)
A. Corbett, A. Wagner, S. Lesgold, H. Ulrich, and S. Stevens. Proceedings of the 7th international conference on Learning sciences, page 99--105. International Society of the Learning Sciences, (2006)
K. Boyer, E. Ha, R. Phillips, M. Wallis, M. Vouk, and J. Lester. Proceedings of the Fourth Workshop on Innovative Use of NLP for Building Educational Applications, page 19--26. Stroudsburg, PA, USA, Association for Computational Linguistics, (2009)