@CONFERENCE\{IMM1981-0354,
    author       = "H. Juel",
    title        = "Hull properties in location problems",
    year         = "1981",
    booktitle    = "2nd International Symposium on Locational Decisions",
    volume       = "",
    series       = "",
    editor       = "",
    publisher    = "",
    organization = "",
    address      = "",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/354-full.html"
}