@article {DBLP:journals/ipl/PedreschiR98,
	title = {Weakest Preconditions for Pure Prolog Programs},
	journal = {Inf. Process. Lett.},
	volume = {67},
	number = {3},
	year = {1998},
	pages = {145-150},
	author = {Dino Pedreschi and Salvatore Ruggieri}
}
