Long-term variability of AGN at hard X-rays S. Soldi, V. Beckmann, W. H. Baumgartner, G. Ponti, C. R. Shrader, P. Lubiński, H. A. Krimm, F. Mattana and J. Tueller A&A, 563 (2014) A57 Published online: 06 March 2014 DOI: 10.1051/0004-6361/201322653