@inproceedings{CLP-1990-Harel90,
	author        = "David Harel",
	booktitle     = "{Proceedings of the Seventh International Conference on Logic Programming}",
	isbn          = "0-262-73090-1",
	pages         = "772--773",
	publisher     = "{MIT Press}",
	title         = "{How Hard Is It to Reason about Propositional Programs?}",
	year          = 1990,
}