WARRINGTON, E. Michael et al. Aspects of HF radio propagation. Annals of Geophysics, [S. l.], v. 52, n. 3-4, p. 301–321, 2009. DOI: 10.4401/ag-4577. Disponível em: https://www.annalsofgeophysics.eu/index.php/annals/article/view/4577. Acesso em: 13 may. 2026.