A. Kumar, and A. Maries. Proceeding of the 2007 conference on Artificial Intelligence in Education, page 596--598. Amsterdam, The Netherlands, The Netherlands, IOS Press, (2007)
B. Steichen, S. Lawless, A. O'Connor, and V. Wade. HT '09: Proceedings of the 20th ACM conference on Hypertext and hypermedia, page 119--128. New York, NY, USA, ACM, (2009)
Y. Bengio, J. Louradour, R. Collobert, and J. Weston. ICML '09: Proceedings of the 26th Annual International Conference on Machine Learning, page 41--48. New York, NY, USA, ACM, (2009)