Hard X-ray variability of V404 Cygni during the 2015 outburst C. Sánchez-Fernández, J. J. E. Kajava, S. E. Motta and E. Kuulkers A&A, 602 (2017) A40 Published online: 02 June 2017 DOI: 10.1051/0004-6361/201629620