A. Delteil, C. Faron, and R. Dieng. Proceedings of the 10th International Conference on Conceptual Structures (ICCS 2002), volume 2393 of Lecture Notes in Computer Science, page 191-204. Springer, (2002)
O. Gerbé, and G. Mineau. Proceedings of the 10th International Conference on Conceptual Structures (ICCS 2002), volume 2393 of Lecture Notes in Computer Science, page 205-219. Springer, (2002)