1. Bleier T and Freund F (2005). Impending earthquake have been sending us warning signals and people are starting to listen. IEEE, Spectrum Int12: 17–21.
2. Bureau of Geology and Mineral Resources of Hebei Province (1989). Regional Geology of Hebei Province. Geological Publishing House, Beijing, 566–584 (in Chinese).
3. Huang Q (2002). One possible generation mechanism of co-seismic electric signals. Proceedings of the Japan Academy78(7): 173–178.
4. Johnston M and Uyeda S (1999). Electromagnetic methods for monitoring earthquakes and volcanic eruptions. IUGG99 Abstract. Birmingham, July 19–30, A72–A83.
5. Ma X Y (1989). Lithospheric Dynamics Atlas of China. China Cartographic Publishing House, Beijing, 20 (in Chinese with English abstract).