@inproceedings{NACLP-1989-Harland,
	author        = "James Harland",
	booktitle     = "{Proceedings of the North American Conference on Logic Programming, 2 Volumes}",
	isbn          = "0-262-62064-2",
	pages         = "626--642",
	publisher     = "{MIT Press}",
	title         = "{A Kripke-like Model for Negation as Failure}",
	year          = 1989,
}