1. The regular geomagnetic-field variations during quiet solar conditions;Campbell,1989
2. The solar and lunar diurnal variation of the earth magnetism;Chapman;London: Philos Trans Roy Soc,1919
3. The diurnal variation of terrestrial magnetism;Shuster;London: Philos Trans,1889
4. External Sq currents in the India–Siberia region;Campbell;J Geophys Res,1993
5. An introduction to induction anomalies;Schmucker;J Geomag Geoelectr,1970