@ARTICLE(	VRS91,
	AUTHOR = "Van Gelder, Allen and Ross, Kenneth A. and Schlipf, John S.",
	TITLE = "The Well-Founded Semantics for General Logic Programs",
	JOURNAL = "Journal of the ACM",
	VOLUME = "38", NUMBER = "3",
	PAGES = "620--650",
	NOTE = "Preliminary abstract appeared in 1988
		(7th) {ACM} Symposium on Principles of Database Systems.",
	YEAR = "1991" )