1. Balthasar, H.: 1988, Astron.Astrophys. Suppl.Ser. 72, 473
2. Duvall, T.L.: 1977, ?A Study of Large-Scale Solar Magnetic and Velocity Fields?, Ph.D. Dissertation, Stanford University, SUIPR Report No. 724
3. Grigoryev, V.M., Demidov, M.L.: 1987, Solar Phys. 114, 147
4. Hoeksema, J.T.: 1984, ?Structure and Evolution of the Large-Scale Solar and Heliospheric Magnetic Fields?, Ph.D. Dissertation, Stanford University, CSSA-ASTRO-84-07
5. Kotov, V.A., Severny, A.B.: 1983, in ?Mean Magnetic Field of the Sun as a Star. Catalogue 1968?1976?, Material from World Data Centre B, Moscow.