@inproceedings{JICSLP-1992-GabbrielliLM,
	author        = "Maurizio Gabbrielli and Giorgio Levi and Maria Chiara Meo",
	booktitle     = "{Proceedings of the Joint International Ninth Conference and Symposium on Logic Programming}",
	isbn          = "0-262-51064-2",
	pages         = "131--145",
	publisher     = "{MIT Press}",
	title         = "{Observational Equivalences for Logic Programs}",
	year          = 1992,
}