@article{Lefèvre:3017,
      author        = "Lefèvre, Laure and Vennerstrøm, Susanne and Dumbović,
                       Mateja and Vršnak, Bojan and Sudar, Davor and Arlt, Rainer
                       and Clette, Frédéric and Crosby, Norma",
      title         = "{Detailed Analysis of Solar Data Related to Historical
                       Extreme Geomagnetic Storms: 1868 - 2010}",
      year          = "2016",
}