ONDRÁŠKOVÁ, Adriena; ŠEVČÍK, Sebastián; KOSTECKÝ, Pavel. A significant decrease of the fundamental Schumann resonance frequency during the solar cycle minimum of 2008-9 as observed at Modra Observatory. Contributions to Geophysics and Geodesy, [S. l.], v. 39, n. 4, p. 345–354, 2009. DOI: 10.2478/v10126-009-0013-5. Disponível em: https://journals.savba.sk/index.php/cgg/article/view/5116. Acesso em: 4 feb. 2026.