L. L. Romachkova, V. G. Kossobokov, G. F. Panza and G. Costa, “Intermediate-Term Predictions of Earthquakes in Italy: Algorithm M8,” Journal of Pure and Applied Geophysics, Vol. 152, No. 1, 1998, pp. 37-55.
 V. I. Larkina, A. V. Nalivayko and N. I. Gershenzon, “Some Statistical Results on Very Low Frequency Radio Wave Emissions in the Upper Ionosphere over Earthquake Zones,” Physics of the Earth and Planetary Interiors, Vol. 57, No. 1-2, 1989, pp. 100-109.
 M. Parrot, “Statistical Study of ELF/VLF Emission Recorded by a Low-Altitude Satellite during Seismic Events,” Journal of Geophysical Research, Vol. 99, No. A12, 1994, pp. 23339-23347. doi:10.1029/94JA02072
 M. A. Fenoglio, A. C. Fraser-Smith, G. C. Beroza and M. J. S. Johnston, “Comparison of Ultra-Low Frequency Electromagnetic Signals with Aftershock Activity during the 1989 Loma Prieta Earthquake Sequence,” Bulletin of the Seismological Society of America, Vol. 83, No. 2, 1993, pp. 347-357.
 P. Varotsos, S. Uyeda and K. Alexopoulos, “Prediction of Recent Destructive Seismic Activities in Greece Based on Seismic Electric Signals,” In: M. Hayakawa and Y. Fujianawa, Electro-Magnetic Phenomena Related to Earthquake Prediction, TERRAPUB, Tokyo, 1994, pp. 13-24.
 C. Y. Wang, P. N. Sundaram and R. E. Goodman, “Electrical Resistivity Changes in Rocks during Frictional Sliding and Fracture,” Pure and Applied Geophysics, Vol. 116, No. 4-5, 1978, pp. 717-731. doi:10.1007/BF00876534
 R. F. Corwin and H. F. Morrison, “Self-Potential Variations Preceding Earthquakes in Central California,” Geophysical Research Letters, Vol. 4, No. 4, 1995, pp. 171-174. doi:10.1029/GL004i004p00171
 P. Varotsos and K. Alexopoulous, “Physical Properties of the Variations of the Electric Field of the Earth Preceding Earthquakes,” Tectophysics, Vol. 110, No. 1-2, 1984, pp. 73-98. doi:10.1016/0040-1951(84)90059-3
 S. K. Park, M. J. S. Johnston, T. R. Madden, F. D. Morgan and H. F. Morrison, “Electromagnetic Precursors to Earthquakes in the ULF Band: A Review of Observations and Mechanisms,” Reviews of Geophysics, Vol. 31, No. 2, 1993, pp. 117-132. doi:10.1029/93RG00820
 M. A. Fenoglio, M. J. S. Johnston and J. D. Byerlee, “Magnetic and Electric-Fields Associated with Changes in High Pore Pressure in Fault Zones—Application to the Loma-Prieta Ulf Emissions,” Journal of Geophysical Research: Solid Earth, Vol. 100, No. B7, 1995, pp. 12951-12958.
 H. Mizutani, T. Ishido, T. Yokokura and S. Ohnishi, “Electrokinetic Phenomena Associated with Earthquakes,” Geophysical Research Letters, Vol. 3, No. 7, 1976, pp. 365-368. doi:10.1029/GL003i007p00365