@ARTICLE\{IMM2003-01239,
    author       = "M. Jacobsen and P. C. Hansen and M. A. Saunders",
    title        = "Subscpace preconditioned {LSQR} for discrete ill-posed problems",
    year         = "2003",
    pages        = "975-989",
    journal      = "BIT",
    volume       = "43",
    editor       = "",
    number       = "",
    publisher    = "",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/1239-full.html"
}