@ARTICLE\{IMM1997-01882,
    author       = "M. R. Hansen and Z. Chaochen",
    title        = "Duration Calculus: Logical Foundations",
    year         = "1997",
    pages        = "283-330",
    journal      = "Formal Aspects of Computing",
    volume       = "9",
    editor       = "",
    number       = "",
    publisher    = "",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/1882-full.html"
}