XMM-Newton observation of the Lockman Hole - II. Spectral analysis V. Mainieri, J. Bergeron, G. Hasinger, I. Lehmann, P. Rosati, M. Schmidt, G. Szokoly and R. Della Ceca A&A, 393 2 (2002) 425-438 Published online: 23 September 2002 DOI: 10.1051/0004-6361:20020991