@article{Vennerstrom:3018,
      author        = "Vennerstrom, S. and Lefèvre, L and  Dumbović, M. and
                       Crosby, N. and Malandraki, O.; and Patsou, I. and Clette,
                       F. and Veronig, A. and Vršnak, B. and Leer, K. and
                       Moretto, T.",
      title         = "{Extreme Geomagnetic Storms - 1868 - 2010}",
      year          = "2016",
}