G. Muzny, M. Fang, A. Chang, and D. Jurafsky. Proceedings of the 15th Conference of the European Chapter of the Association for Computational Linguistics: Volume 1, Long Papers, page 460--470. Valencia, Spain, Association for Computational Linguistics, (April 2017)
K. Boyer, E. Ha, M. Wallis, R. Phillips, M. Vouk, and J. Lester. Proceeding of the 2009 conference on Artificial Intelligence in Education: Building Learning Systems that Care: From Knowledge Representation to Affective Modelling, page 141--148. Amsterdam, The Netherlands, The Netherlands, IOS Press, (2009)