@inproceedings{TOOLS-USA-1991-PaulaN,
	author        = "Everton G. de Paula and Michael L. Nelson",
	booktitle     = "{Proceedings of the Fifth International Conference on Technology of Object-Oriented Languages and Systems}",
	isbn          = "0-13-923178-1",
	pages         = "203--218",
	publisher     = "{Prentice Hall}",
	title         = "{Designing a Class Hierarchy}",
	year          = 1991,
}