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)
S. Polovina, and R. Hill. Proceedings of the 13th International Conference on Conceptual Structures (ICCS 2005), volume 3596 of Lecture Notes in Computer Science, page 439-452. Springer, (2005)