@inproceedings{KR-1991-Rich,
	author        = "Charles Rich",
	booktitle     = "{Proceedings of the Second International Conference on Principles of Knowledge Representation and Reasoning}",
	isbn          = "1-55860-165-1",
	pages         = "591--592",
	publisher     = "{Morgan Kaufmann}",
	title         = "{Implemented Knowledge Representation and Reasoning Systems: An Endangered Species?}",
	year          = 1991,
}