XMM-Newton spectral properties of the ultraluminous IRAS galaxy Mrk 273 I. Balestra, Th. Boller, L. Gallo, D. Lutz and S. Hess A&A, 442 2 (2005) 469-478 Published online: 07 October 2005 DOI: 10.1051/0004-6361:20053558