1. The world magnetic charts of the epoch 1960;Altshuler;Geomag. Aeronom.,1964
2. Spherical harmonic analysis of the world magnetic charts of the epoch 1960;Adam;Geomag. Aeronom.,1964
3. Summary of the magnetic elements at the equidistant points and epochs;Weinberg,1970
4. An analysis of the earth's magnetic field from 1835 to 1965;McDonald;ESSA Technical Report, 46-IES,1967
5. Die Elemente des Erdmagnetismus für die Epochen 1600, 1650, 1700, 1780, 1842, 1885;Fritshe,1889