LEITINGER, R. Ionospheric electron content: the European perspective. Annals of Geophysics, [S. l.], v. 41, n. 5-6, 1998. DOI: 10.4401/ag-3816. Disponível em: https://www.annalsofgeophysics.eu/index.php/annals/article/view/3816. Acesso em: 21 feb. 2024.