@conference {DBLP:conf/dood/GiannottiPSZ91,
	title = {Non-Determinism in Deductive Databases},
	booktitle = {DOOD},
	year = {1991},
	pages = {129-146},
	author = {Fosca Giannotti and Dino Pedreschi and Domenico Sacc{\`a} and Carlo Zaniolo}
}
