R. Gallant, and M. Lehman. Engineering of Computer Based Systems, 2008. ECBS 2008. 15th Annual IEEE International Conference and Workshop on the, page 473--482. (2008)
J. Howse. Proceedings of the 16th International Conference on Conceptual Structures (ICCS 2008), volume 5113 of Lecture Notes in Computer Science, page 1-20. Springer, (2008)