1. Altschuler, M. D., Trotter, D. E., and Orrall, F. Q.: 1972, Solar Phys. 26, 354.
2. Avrett, E. H., Vernazza, J. E., and Linsky, J. L.: 1976, Astrophys. J., submitted.
3. Bertaux, J. L., Blamont, J. E., and Festou, M.: 1973, Astron. Astrophys. 25, 415.
4. Bohlin, J. D.: 1970, Solar Phys. 12, 240.
5. Bohlin, J. D., Koomen, M. J., and Tousey, R.: 1971, Solar Phys. 21, 408.