H. Schärfe. Proceedings of the 10th International Conference on Conceptual Structures (ICCS 2002), volume 2393 of Lecture Notes in Computer Science, page 166-176. Springer, (2002)
C. Hookway. Proceedings of the 15th International Conference on Conceptual Structures (ICCS 2007), volume 4604 of Lecture Notes in Artificial Intelligence, page 59-68. Berlin, Heidelberg, Springer-Verlag, (July 2007)