Martin Gogolla Cris Kobryn «UML» 2001 - The Unified Modeling Language, Modeling Languages, Concepts, and Tools, 4th International Conference, Toronto, Canada, October 1-5, 2001, Proceedings 3-540-42667-1 UML Lecture Notes in Computer Science 2185 Springer 2001 db/conf/uml/uml2001.html