6GOLOVIN A N, GOLOVKOV V P, ROTANOVA N M. On the separation of the field variations into the drifting and non - drifting components[J] .J Geomag Geoelectr, 1991,43:307-317.
7LOWES F J. Spatial power spectrum of the main geomagnetic field and extrapolation to the core[J]. Geophys J R Astron Soc, 1974,34:717-730.
8BENTON E R, ALLDREDGE L R. On the interpretation of the geomagnetic energy spectrum[J]. Phys Earth Planet Inter, 1987,48:265-278.
9NEVANLINNA H. Notes on global mean - square values of the geomagnetic field and secular variation[J]. J Geomag Geoelectr, 1987,39: 165-174.
10MEYER J. Remark on the secular change in the energy density spectrum of the geomagnetic field[J]. J Geomag Geoelectr, 1986,38:165-169.
