[1] Etienne Wenger. Artificial Intelligence and Tutoring Systems. Morgan Kaufmann, Los Altos, CA, 1987.

[2] J. S. Brown and R. R. Burton. Diagnostic models for procedural bugs in basic mathematical skills. Cognitive Science, 2:155-191, 1978.

[3] J. S. Brown, R. R. Burton, C. L. Hausman, I. Goldstein, B. Huggins, and M. L. Miller. Aspects of a Theory for Automated Student Modeling. BBN Report 3549 (ICAI Report 4). Bolt, Beranek and Newman, Inc., Cambridge, MA, 1977.

[4] J. S. Brown, R. R. Burton, M. L. Miller, J. de Kleer, S. Purcell, C. L. Hausman, and R. Bobrow. Steps toward a Theoretical Foundation for Complex Knowledge-Based CAI. BBN Report 3135 (ICAI Report 2). Bolt, Beranek and Newman, Inc., Cambridge, MA, 1975.

[5] R. Burton, Diagnosing bugs in a simple procedural skill. In D.H. Sleeman, and J.S. Brown (Eds.) Intelligent Tutoring Systems. Academic Press, London.