1. Anderson, John R., C. Franklin Boyle, and Gregg Yost: 1985, ?The Geometry Tutor?. In Proceedings of the Ninth International Joint Conference on Artificial Intelligence, Los Angeles, California, August, pp. 1?7.
2. Douglas E. and Martha E. Pollack: 1991, ?Weighted Abduction for Plan Ascription?. User Modeling and User-Adapted Interaction 1, in press.
3. Brown, John Seely and Richard R. Burton: 1978, ?Diagnostic Models for Procedural Bugs in Basic Mathematical Skills?. Cognitive Science 2, 155?192.
4. Technical Report CS-89-37;Randall J. Calistri,1989
5. PhD thesis;Randall J. Calistri,1990