HOFFMAN, Michal. Preliminary catalogue of natural and anthropogenic VLF radio spectral patterns. Contributions to Geophysics and Geodesy, [S. l.], v. 53, n. 2, p. 151–166, 2023. DOI: 10.31577/congeo.2023.53.2.4. Disponível em: https://journal.geo.sav.sk/cgg/article/view/448. Acesso em: 13 aug. 2025.