@inproceedings{UML-1999-RichtersG,
	author        = "Mark Richters and Martin Gogolla",
	booktitle     = "{Proceedings of the Second International Conference on the Unified Modeling Language: Beyond the Standard}",
	doi           = "10.1007/3-540-46852-8_12",
	editor        = "Robert B. France and Bernhard Rumpe",
	pages         = "156--171",
	publisher     = "{Springer-Verlag}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{A Metamodel for OCL}",
	volume        = 1723,
	year          = 1999,
}