@article{Soldi:2014,
  author  = "S. Soldi and V. Beckmann and W. Baumgartner and G. Ponti and C. Shrader and P. Lubiński and H. Krimm and F. Mattana and J. Tueller",
  title   = "Long-term variability of AGN at hard X-rays",
  journal = "Astronomy & Astrophysics",
  volume  = "Vol. 563",
  pages   = "1--16",
  year    = "2014",
}