@ARTICLE{OkushiVanGelder04-AMAI-persistent,
	Author = "Okushi, Fumiaki and Van Gelder, Allen",
	Title = "Persistent and Quasi-Persistent Lemmas
		in Propositional Model Elimination",
  journal =	"Annals of Mathematics and Artificial Intelligence",
  volume =	"40",
  number =	"3--4",
  pages = 	"373--402",
  year =	 2004
	}