Solovieva M, Rozhnoi A, Fedun V, Schwingenschuh K, Hayakawa M. Ionospheric perturbations related to the earthquake in Vrancea area on November 22, 2014, as detected by electromagnetic VLF/LF frequency signals. Ann. Geophys. 2015;58(5):A0552. doi:10.4401/ag-6827