@TECHREPORT\{IMM2002-01286, author = "M. Jacobsen and P. C. Hansen and M. A. Saunders", title = "Subspace preconditioned {LSQR} for discrete ill-posed problems", year = "2002", pages = "16", number = "", series = "IMM-TR-2002-17", institution = "Informatics and Mathematical Modelling, Technical University of Denmark, {DTU}", address = "Richard Petersens Plads, Building 321, {DK-}2800 Kgs. Lyngby", type = "", url = "http://www2.compute.dtu.dk/pubdb/pubs/1286-full.html" }