1. Banos, G. J. and Macris, C. J.: 1970, Solar Phys.
12, 106.
2. Beckers, J. M.: 1964, Thesis, Utrecht University.
3. Bray, R. J. and Loughhead, R. E.: 1974, The Solar Chromosphere, Chapman and Hall, London.
4. Dunn, R. B.: 1960, Thesis, Harvard University.
5. Giovanelli, R. G.: 1974, Solar Phys.
37, 301.