Sorokin, V. M., E. N. Fedorov, A. Yu. Schekotov, O. A. Molchanov, and M. Hayakawa. “Depression of the ULF Geomagnetic Pulsation Related to Ionospheric Irregularities”. Annals of Geophysics 47, no. 1 (December 25, 2004). Accessed December 7, 2021. https://www.annalsofgeophysics.eu/index.php/annals/article/view/3271.