M. Keeler. Proceedings of the 15th International Conference on Conceptual Structures (ICCS 2007), volume 4604 of Lecture Notes in Artificial Intelligence, page 443-459. Berlin, Heidelberg, Springer-Verlag, (July 2007)
M. Keeler. Proceedings of the 12th International Conference on Conceptual Structures (ICCS 2004), volume 3127 of Lecture Notes in Computer Science, page 242-260. Springer, (2004)