Duka, Bejo, Eni Duka, and Klaudio Peqini. “Recovering External Contribution from the Monthly Mean Series of a Given Geomagnetic Observatory”. Annals of Geophysics 59, no. 3 (July 12, 2016): G0321. Accessed March 29, 2024. https://www.annalsofgeophysics.eu/index.php/annals/article/view/6971.