Solovieva, M., A. Rozhnoi, V. Fedun, K. Schwingenschuh, and M. Hayakawa. “Ionospheric Perturbations Related to the Earthquake in Vrancea Area on November 22, 2014, As Detected by Electromagnetic VLF/LF Frequency Signals”. Annals of Geophysics, vol. 58, no. 5, Nov. 2015, p. A0552, doi:10.4401/ag-6827.