R. Hosseini, P. Brusilovsky, M. Yudelson, and A. Hellas. Proceedings of the 25th Conference on User Modeling, Adaptation and Personalization, page 76--84. New York, NY, USA, ACM, (2017)
J. Beck, K. Chang, J. Mostow, and A. Corbett. Intelligent Tutoring Systems, volume 5091 of Lecture Notes in Computer Science, Springer Berlin Heidelberg, (2008)