O. Corby. Proceedings of the 16th International Conference on Conceptual Structures (ICCS 2008), volume 5113 of Lecture Notes in Computer Science, page 43-61. Springer, (2008)
L. Harper, and H. Delugach. Proceedings of the 11th International Conference on Conceptual Structures (ICCS 2003), volume 2746 of Lecture Notes in Computer Science, page 392-404. Springer, (2003)