1. Abhyankar, K. D. and Fymat, A. L.: 1971, Astrophys. J. Suppl. 23, 35.
2. Allen, C. W.: 1963, Astrophysical Quantities, Athlone Press, London, 291 pp.
3. Ambartsumian, V. A.: 1942, Astr. Zh. (Russ.) 19, 30.
4. Ambartsumian, V. A.: 1958, Theoretical Astrophysics, Pergamon Press, New York, 645 pp.
5. Appleby, J. F. and van Blerkom, D. J.: 1974, submitted to Icarus.