1. International Geomagnetic Reference Field Revision 1987;Barraclough;J. geomagn. Geoelect.,1987
2. A revised corrected geomagnetic coordinate system;Gustafsson;Arkiv for Geofysik,1970
3. Corrected geomagnetic coordinates for Epoch 1980;Gustaffson,1984
4. Tables and maps of geomagnetic coordinates corrected by the higher order spherical harmonics terms;Hakura;Rept Ionos. Space Res. Japan,1965
5. The spherical harmonic development of the geomagnetic field, Epoch 1945, transformed into rectangular geomagnetic coordinate systems;Hultqvist;Arkiv for Geofysik,1958