@TECHREPORT\{IMM1999-01704,
    author       = "H. A. Nielsen and T. S. Nielsen and A. K. Joensen and H. Madsen and J. Holst",
    title        = "Tracking time-varying coefficient-functions",
    year         = "1999",
    number       = "9",
    series       = "",
    institution  = "Department of Mathematical Modelling, Technical University of Denmark, {DK-}2800 Lyngby, Denmark",
    address      = "",
    type         = "",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/1704-full.html"
}