G. Brajnik and C. Tasso. A shell for developing non-monotonic user modeling systems.Int. J. Human-Computer Studies, 40:31–62, 1994.
T. W. Finin. GUMS: A general user modeling shell. In A. Kobsa and W. Wahlster, editors,User Models in Dialog Systems, pages 411–430. Springer, Berlin, Heidelberg, 1989.
Xueming Huang, Gordon I. McCalla, Jim E. Greer, and Eric Neufeld. Revising deductive knowledge and stereotypical knowledge in a student model.User Modeling and User-Adapted Interaction, 1(1):87–115, 1991.
H. Vergara. Protum: A prolog based tool for user modeling. WIS Memo 10, WG Knowledge-Based Information Systems, Department of Information Science, University of Konstanz, Germany, 1994.
M. Ikeda Y. Kono and R. Mizoguchi. Themis: A nonmonotonic inductive student modeling system.Journal of Artificial Intelligence in Education, 5(3), 1994.