G. E. Backus, Kinematics of Geomagnetic Secular Variation in a Perfectly Conducting Core, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol.263, issue.1141, pp.239-266, 1968.
DOI : 10.1098/rsta.1968.0014

G. E. Backus, Bayesian inference in geomagnetism, Geophysical Journal International, vol.92, issue.1, pp.125-142, 1988.
DOI : 10.1111/j.1365-246X.1988.tb01127.x

G. E. Backus and J. L. Le-mouel, The region on the core-mantle boundary where a geostrophic velocity field can be determined from, 1986.

F. S. Barker and D. R. Barraclough, The effects of the non-uniform distribution of magnetic observatory data on secular variation Modelling the geomagnetic field, J. Geomag. Geoelectr, vol.42, pp.1051-1070, 1985.

E. R. Benton and J. Bloxham, On the coupling of fluid dynamics and electromagnetism at the top of the Earth's core Simple models of fluid flow at the core surface derived from geomagnetic field models, Geophys, Geophys. Astrophys. Fluid Dyn. J . Int, vol.99, pp.173-182, 1985.

J. Bloxham and D. Gubbins, The secular variation of Earth's magnetic field, Nature, vol.313, issue.6040, pp.777-781, 1985.
DOI : 10.1038/317777a0

J. Bloxham and D. Gubbins, Geomagnetic field analysis-IV. Testing the frozen-flux hypothesis, Geophysical Journal International, vol.84, issue.1, pp.139-152, 1986.
DOI : 10.1111/j.1365-246X.1986.tb04349.x

J. Bloxham and A. Jackson, Simultaneous stochastic inversion for geomagnetic main field and secular variation, J. geophys, vol.2, pp.1820-1980, 1989.
DOI : 10.1029/jb094ib11p15753

J. Bloxham, D. Gubbins, and A. Jackson, Geomagnetic Secular Variation, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol.329, issue.1606, pp.415-502, 1989.
DOI : 10.1098/rsta.1989.0087

E. Bullard and H. Gellmann, Homogeneous Dynamos and Terrestrial Magnetism, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol.247, issue.928, pp.213-278, 1954.
DOI : 10.1098/rsta.1954.0018

Y. Cohen and J. Achache, New global vector magnetic anomaly maps derived from Magsat data, Journal of Geophysical Research, vol.90, issue.B7, pp.10783-10800, 1990.
DOI : 10.1029/JB095iB07p10783

J. L. Counil, Y. Cohen, and J. Achache, The global continent-ocean magnetization contrast, Earth and Planetary Science Letters, vol.103, issue.1-4, pp.354-364, 1991.
DOI : 10.1016/0012-821X(91)90172-E

J. A. Gaunt, The Triplets of Helium, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol.228, issue.659-669, pp.151-196, 1929.
DOI : 10.1098/rsta.1929.0004

C. Gire and J. L. Le-mouel, Tangentially geostrophic flow at the core-mantle boundary compatible with the observed geomagnetic, 1990.

C. Gire, L. Mouel, J. L. Madden, and T. , Motions at the core surface derived from SV data, Geophysical Journal International, vol.84, issue.1, pp.1-29, 1986.
DOI : 10.1111/j.1365-246X.1986.tb04342.x

D. Gubbins, Finding Core Motions from Magnetic Observations [and Discussion], Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol.306, issue.1492, pp.247-254, 1982.
DOI : 10.1098/rsta.1982.0084

D. Gubbins, Dynamics of the secular variation, Physics of the Earth and Planetary Interiors, vol.68, issue.1-2, pp.170-182, 1991.
DOI : 10.1016/0031-9201(91)90016-B

G. Hulot, L. Mouel, J. L. Jault, D. Jault, D. Le-mouel et al., The flow at the core mantle boundary: symmetry properties Physical properties at the top of the earth's core and core surface motions, Phys A geomagnetic field spectrum, J. Geomag. Geoelectr. Earth planet Inter. Geophys. Res. Lett, vol.42, issue.9, pp.250-253, 1982.

R. A. Langel, R. H. Estes, and G. D. Mead, Some new methods in geomagnetism field modelling applied to the 1960-1980 epoch, J, 1982.

R. A. Langel, D. J. Kerridge, D. R. Barraclough, and S. R. Malin, Geomagnetic temporal change: 1903-1982, A spline representation., Journal of geomagnetism and geoelectricity, vol.38, issue.6, 1986.
DOI : 10.5636/jgg.38.573

L. Mouel, J. L. Gire, C. Madden, T. Lloyd, D. Gubbins et al., Motions at the core surface in the geostrophic approximation Toroidal fluid motion at the top of the earth's core, Geophys. 1. Int, Phys. Earth planet. Inter, vol.39, issue.100, pp.455-467, 1985.

F. J. Lowes, Mean square values on sphere of spherical harmonic vector fields, 1. geophys. Res, pp.71-2179, 1966.

F. J. Lowes, The limitations of numerical models of the main geomagnetic field., Journal of geomagnetism and geoelectricity, vol.42, issue.9, pp.1071-1078, 1990.
DOI : 10.5636/jgg.42.1071

N. W. Peddie and E. B. Fabiano, A proposed international geomagnetic reference field for 1965-1985, J. Geomag. Geoelectr, vol.34, 1982.

N. W. Peddie and E. B. Fabiano, Assessment of models proposed for the 1981 revision of the IGRF On analysis of the secular variation, Geomag. Geoelectr. J. Geomag. Geoelectr, vol.1, issue.17, pp.137-151, 1965.

S. Scott, S. Runcom, and C. V. Voorhies, The Gaunt and Elsasser Integrals in the Application of Modern Physics to the Earth's and Planetary Interiors Steady flows at the top of the core derived from geomagnetic field models, J . geophys. Res, vol.91, pp.12444-12466, 1969.

K. A. Whaler, Does the whole of the Earth's core convect?, Nature, vol.287, issue.5782, pp.528-530, 1980.
DOI : 10.1038/287528a0

K. A. Whaler and S. O. Clarke, A steady velocity field at the top of the earth's core in the frozen flux approximation, Geophys. J. lnt., frozen-flux magnetic data, Geophys, J. R. astr. SOC. models, Phys. Earth planet. Inter, vol.85, issue.33, pp.617-628, 1988.

. Res, 15 753-15 769. secular variation: The large scale component of the flow, Phys. Earth planet. Inter, vol.94, issue.59, pp.259-287