I. Guy, I. Ronen, und E. Wilcox. Proceedings of the 14th International Conference on Intelligent User Interfaces, Seite 77--86. New York, NY, USA, ACM, (2009)
D. Bernhard, und I. Gurevych. Proceedings of the Third Workshop on Innovative Use of NLP for Building Educational Applications, Seite 44--52. Stroudsburg, PA, USA, Association for Computational Linguistics, (2008)