Cumulative hard X-ray spectrum of local AGN: a link to the cosmic X-ray background S. Sazonov, R. Krivonos, M. Revnivtsev, E. Churazov and R. Sunyaev A&A, 482 2 (2008) 517-527 Published online: 04 March 2008 DOI: 10.1051/0004-6361:20078537