Wray, R. E., & Laird, J. (1998). Maintaining consistency in hierarchical reasoning. In Proceedings of the 15th National Conference on Artificial Intelligence**, pp. 928–935.**
Wray, R. E., Laird, J., & Jones, R. M. (1996). Compilation of non-contemporaneous constraints. In Proceedings of the 13th National Conference on Artificial Intelligence**, pp.**
771–778.

Wray, R. E., Laird, J. E., Nuxoll, A., & Jones, R. M. (2002). Intelligent opponents for virtual reality trainers. In **Proceedings of the Interservice/Industry Training, Simulation and** Education Conference (I/ITSEC) 2002.