Stanislawska, I., G. Juchnikowski, and L. R. Cander. “The Kriging Method of Ionospheric Parameter f0F2 Instantaneous Mapping”. Annals of Geophysics 39, no. 4 (November 25, 1996). Accessed April 26, 2024. https://www.annalsofgeophysics.eu/index.php/annals/article/view/4007.