P. Hitzler, and M. Krötzsch. Proceedings of the 14th International Conference on Conceptual Structures (ICCS 2006), volume 4068 of Lecture Notes in Computer Science, page 260-273. Springer, (2006)
J. Tane, P. Cimiano, and P. Hitzler. Proceedings of the 14th International Conference on Conceptual Structures (ICCS 2006), volume 4068 of Lecture Notes in Computer Science, page 413-426. Springer, (2006)