1. Allen, C. W.: 1963,Astrophysical Quantities, The Athlone Press, London.
2. Clayton, D. D.: 1968,Principles of Stellar Evolution and Nucleosynthesis, McGraw-Hill Book Company, New York.
3. Cox, A. N.: 1973, private communication.
4. Cox, A. N. and Stewart, J. N.: 1970,Astrophys. J. Suppl. 19, No. 174.
5. de Vaucouleurs, G. and de Vaucouleurs, A.: 1964,Reference Catalogue of Bright Galaxies, The University of Texas Press, Austin.