@MISC\{IMM2002-0524,
    author       = "S. S. Nielsen",
    title        = "An Introduction to the {GAMS} Modeling System",
    year         = "2002",
    month        = "jun",
    publisher    = "",
    address      = "",
    url          = "http://www.imm.dtu.dk/~sn/ps_files/GamsIntro.pdf"
}