@inproceedings{ILPS-1993-BarbackL,
	author        = "Monica D. Barback and Jorge Lobo",
	booktitle     = "{Proceedings of the International Symposium on Logic Programming}",
	isbn          = "0-262-63152-0",
	pages         = "651",
	publisher     = "{MIT Press}",
	title         = "{A Proof Procedure for Default Theories with Extensions}",
	year          = 1993,
}