@inproceedings{ICLP-1999-Greco,
	author        = "Sergio Greco",
	booktitle     = "{Proceedings of the 15th International Conference on Logic Programming}",
	isbn          = "0-262-54104-1",
	pages         = "441--455",
	publisher     = "{MIT Press}",
	title         = "{Optimization of Disjunctive Queries}",
	year          = 1999,
}