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://journals.savba.sk/index.php/cgg/article/view/5415. Acesso em: 4 feb. 2026.