Schlamminger, L. (1992) The Journal of Atmospheric and Solar-Terrestrial Physics, 54, 989-993.https://doi.org/10.1016/0021-9169(92)90065-S
Eddy, J. A. (1976). The maunder minimum. Science, 192, 1189–1202. https://doi.org/10.1126/science.192.4245.1189 Fritz, H. (1873). Verzeichniss Beobachteter Polarlichter