1. E. C. G. Sudarshan:Fields Quanta,2, 175 (1972); lecture at theLatin American Summer School, University of Mexico, 1972 (unpublished);C. A. Nelson andE. C. G. Sudarshan:Phys. Rev. D,6, 3658, 3678 (1972);A. M. Gleeson, R. J. Moore, H. Rechenberg andE. C. G. Sudarshan:Phys. Rev. D,4, 2242 (1971);C. C. Chiang:Phys. Rev. D,7, 1725 (1973);J. L. Richard:Phys. Rev. D,7, 3617 (1973).
2. C. C. Chiang:Phys. Rev. D,8, 1025 (1973).
3. C. C. Chiang, J. J. Dykla andA. E. Hwang:Phys. Rev. D,10, 1085 (1974).
4. See, for instance,Ya. B. Zeldovich andI. D. Novikov:Relativistic Astrophysics. — VI:Stars and Relativity, Chap. X (Chicago, Ill., 1971).
5. Here we refer to the concept of secular stability; namely we ask if an equilibrium configuration of a star is stable against small arbitrary adiabatic perturbations. Compare, for instance,H. Y. Chiu:Stellar Physics, Vol.6, Chap. II (Waltham, Mass., 1968).