@MISC\{IMM1997-0656,
    author       = "H. B. Nielsen",
    title        = "Direct Methods for Sparse Matrices",
    year         = "1997",
    month        = "jan",
    pages        = "44",
    publisher    = "Informatics and Mathematical Modelling, Technical University of Denmark, {DTU}",
    address      = "Richard Petersens Plads, Building 321, {DK-}2800 Kgs. Lyngby",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/656-full.html"
}