1. Anzer, U.: 1969, Solar Phys. 8, 37.
2. Cowling, T. G.: 1953, ‘Solar Electrodynamics’, in The Sun (ed. by G. P. Kuiper), University of Chicago Press, Chicago, Illinois, pp. 532–543.
3. Doherty, L. R. and Menzel, D. H.: 1965, Astrophys. J. 141, 251.
4. Dunn, R. B.: 1960, Thesis, Harvard University.
5. Field, G. B.: 1965, Astrophys. J. 142, 531.