@conference {DBLP:conf/slp/MancarellaPRT90,
	title = {Algebraic Properties of a Class of Logic Programs},
	booktitle = {NACLP},
	year = {1990},
	pages = {23-39},
	author = {Paolo Mancarella and Dino Pedreschi and Marina Rondinelli and Marco Tagliatti}
}
