Hard X-ray emission from the Galactic ridge R. Krivonos, M. Revnivtsev, E. Churazov, S. Sazonov, S. Grebenev and R. Sunyaev A&A, 463 3 (2007) 957-967 Published online: 05 December 2006 DOI: 10.1051/0004-6361:20065626