1. On the gravitational field of a mass point according to Einstein’s theory;Schwarzschild;Sitz. Deut. Akad. Wiss. Berlin Kl. Math. Phys.,1916
2. Static solutions of Einstein’s field equations for spheres of fluid;Tolman;Phys. Rev.,1939
3. L’univers en expansion;Lemaître;Ann. Soc. Sci. Brux. A,1933
4. On massive neutron cores;Oppenheimer;Phys. Rev.,1939
5. Anisotropic spheres in general relativity;Bowers;Astrophys. J.,1974