@ARTICLE\{IMM1994-02780,
    author       = "M. Rostgaard and N. k. Poulsen and O. Ravn",
    title        = "Spectral factorization using the delta operator",
    year         = "1994",
    pages        = "293-301",
    journal      = "Systems and Control Letters",
    volume       = "22",
    editor       = "",
    number       = "5",
    publisher    = "",
    note         = "Also technical report no. 14/92, {IMSOR,} {DTU}",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/2780-full.html"
}