1. Andersen, B.N., Leifsen, T.E., Toutain, T.: Sol. Phys. 152, 247 (1994)
2. Berrilli, F., Del Moro, D., Viticchiè, B.: Astron. Astrophys. 489, 763 (2008)
3. Fröhlich, C.: In: Pap, J.M., et al. (eds.) IAU Colloq. 143, The Sun as a Variable Star: Solar and Stellar Irradiance Variations, p. 28. Cambridge Univ. Press, Cambridge (1994)
4. Fröhlich, C., Lean, J.: Geophys. Res. Lett. 25, 4377 (1998)
5. Rabello Soares, M.C., Roca, Cortes T., Jimenez, A., Anderson, B.N., Appourchaux, T.: Astron. Astrophys. 328, 970 (1997)