@inproceedings{BeierleKloosMeyer99,
    author = "Christoph Beierle, Reinhold Kloos and Gregor Meyer",
    title = "A pragmatic type concept for Prolog  supporting
    polymorphism, subtyping, and meta-programming",
    booktitle = "Electronic Notes in Theoretical Computer Science",
    volume = "30",
    issue = "1",
    publisher = "Elsevier Science Publishers",
    editor = "Sandro Etalle and Jan-Georg Smaus",
    year = "2000",
    note="http://www.elsevier.nl/gej-ng/31/29/23/55/23/29"
}