@CONFERENCE\{IMM1993-01609,
    author       = "F. Nielson and H. Riis Nielson",
    title        = "Layered Predicates",
    year         = "1993",
    pages        = "425-456",
    booktitle    = "Proc. {REX'}92 workshop on  Semantics -- foundations and applications",
    volume       = "666",
    series       = "Lecture Notes in Computer Science",
    editor       = "",
    publisher    = "Springer-Verlag",
    organization = "",
    address      = "",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/1609-full.html"
}