1. The Impact of Century-Scale Changes in the Core Magnetic Field on External Magnetic Field Contributions
2. A revised corrected geomagnetic coordinate system;Gustafsson G.;Arkiv för geofysik,1970
3. Tables and maps of geomagnetic coordinates corrected by the higher order spherical harmonic terms;Hakura Y.;Report of Ionosphere and Space Research in Japan,1965
4. The geomagnetic field lines in higher approximation;Hultqvist B.;Arkiv för geofysik,1958