A. Kabbaj. Proceedings of the 14th International Conference on Conceptual Structures (ICCS 2006), volume 4068 of Lecture Notes in Computer Science, page 286-299. Springer, (2006)
R. Hill, S. Polovina, and D. Shadija. Proceedings of the 14th International Conference on Conceptual Structures (ICCS 2006), volume 4068 of Lecture Notes in Computer Science, page 247-259. Springer, (2006)