1. Eggen, O. J. and Greenstein, J. L.: 1965, Astrophys. J. 141, 83.
2. Eggen, O. J. and Greenstein, J. L.: 1967, Astrophys. J. 150, 927.
3. Greenstein, J. L.: 1958, Encyclopedia of Physics
50, 161, Springer-Verlag, Berlin.
4. Greenstein, J. L.: 1960, Stellar Atmospheres (ed. by J. L. Greenstein), University of Chicago Press, Chicago, Chapter xix.
5. Greenstein, J. L. and Trimble, V. L.: 1967, Astrophys. J. 149, 283.