O. Conlan, I. O'Keeffe, and S. Tallon. Proceedings of the 4th international conference on Adaptive Hypermedia and Adaptive Web-Based Systems, page 81--90. Berlin, Heidelberg, Springer-Verlag, (2006)
H. Ashman, T. Brailsford, and P. Brusilovsky. Advances in Web Based Learning ICWL 2009, volume 5686 of Lecture Notes in Computer Science, chapter 1, Springer Berlin / Heidelberg, Berlin, Heidelberg, (2009)