1. Allen, C. W.: 1963, Astrophysical Quantities, Athlon Press, London, p. 164.
2. Avrett, E. H.: 1981, in L. E. Cram and J. H. Thomas (eds.), The Physics of Sunspots, AURA, Sacramento Peak Obs., p. 235.
3. Bai, T.: 1986, Astrophys. J. 308, 912.
4. Barkas, W. H. and Berger, M. J.: 1964, Tables of Energy Losses and Ranges of Heavy Charged Particles, NASA, Washington D.C., p. 131.
5. Bertrand, F. E., Peele, R. W., and Kalbach-Cline, C.: 1974, Phys. Rev. C10, 1028.