@InProceedings{ZaffanellaBH99,
  Author = "E. Zaffanella and R. Bagnara and P. M. Hill",
  Title = "Widening {Sharing}",
  Pages = "414--431",
  Crossref = "PPDP99"
}

@Proceedings{PPDP99,
  Title = "Principles and Practice of Declarative Programming",
  Booktitle = "Principles and Practice of Declarative Programming",
  Address = "Paris, France",
  Year = 1999,
  Editor = "G. Nadathur",
  Publisher = "Springer-Verlag, Berlin",
  Series = "Lecture Notes in Computer Science",
  Volume = 1702,
  ISBN = "3-540-66540-4",
}