@inproceedings{KR-1989-EtheringtonFGIL,
	author        = "David W. Etherington and Kenneth D. Forbus and Matthew L. Ginsberg and David J. Israel and Vladimir Lifschitz",
	booktitle     = "{Proceedings of the First International Conference on Principles of Knowledge Representation and Reasoning}",
	isbn          = "1-55860-032-9",
	pages         = "500--504",
	publisher     = "{Morgan Kaufmann}",
	title         = "{Critical Issues in Nonmonotonic Reasoning}",
	year          = 1989,
}