@article {DBLP:journals/jcss/GiannottiPZ01,
	title = {Semantics and Expressive Power of Nondeterministic Constructs in Deductive Databases},
	journal = {J. Comput. Syst. Sci.},
	volume = {62},
	number = {1},
	year = {2001},
	pages = {15-42},
	author = {Fosca Giannotti and Dino Pedreschi and Carlo Zaniolo}
}
