?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.aulast=Pettorossi&rft.aufirst=Alberto&rft.au=Pettorossi%2C+Alberto&rft.date=2006&rft.btitle=Dagstuhl+Seminar+Proceedings&rft.title=Proofs+of+Program+Properties+via+Unfold%2FFold+Transformations+of+Constraint+Logic+Programs&rft.genre=bookitem