Werner, Rolf, Veneta Guineva, Irina Despirak, Andris Lyubchich, Rumiana Bojilova, Lyubomira Raykova, Atanas Atanassov, and Dimitar Valev. “Statistical Study of Geomagnetic Disturbances at European Auroral and High Latitudes”. Proceedings of the Bulgarian Academy of Sciences 76, no. 4 (April 30, 2023): 571–579. Accessed March 18, 2025. https://www.proceedings.bas.bg/index.php/cr/article/view/295.