F. Amarger, O. Haemmerlé, N. Hernandez, and C. Pradel. Proceedings of the 21th International Conference on Conceptual Structures (ICCS 2013), volume 7735 of Lecture Notes in Computer Science, page 75-89. Springer, (2013)
O. Corby, and C. Faron-Zucker. Proceedings of the 15th International Conference on Conceptual Structures (ICCS 2007), volume 4604 of Lecture Notes in Artificial Intelligence, page 472-475. Berlin, Heidelberg, Springer-Verlag, (July 2007)