N. Moreau, M. Leclère, and M. Croitoru. Proceedings of the 17th International Conference on Conceptual Structures (ICCS 2009), volume 5662 of Lecture Notes in Computer Science, page 233-246. Springer, (2009)
M. Greaves. Proceedings of the 17th International Conference on Conceptual Structures (ICCS 2009), volume 5662 of Lecture Notes in Computer Science, page 1. Springer, (2009)