TY - JOUR A1 - Lundstedt, H. A1 - Persson, T. A1 - Andersson, V. T1 - The extreme solar storm of May 1921: observations and a complex topological model JO - Ann. Geophys. J1 - ANGEO VL - 33 IS - 1 SP - 109 EP - 116 Y1 - 2015/01/27 PB - Copernicus Publications SN - 1432-0576 UR - https://angeo.copernicus.org/articles/33/109/2015/ L1 - https://angeo.copernicus.org/articles/33/109/2015/angeo-33-109-2015.pdf DO - 10.5194/angeo-33-109-2015 ER -