1. Einstein, A.: 1946,The Meaning of Relativity, Princeton.
2. Horák, Z.: 1963a,Bull. Astron. Inst. Czech. 14, 117.
3. Horák, Z.: 1963b,Bull. Astron. Inst. Czech. 14, 119.
4. Møller, C.: 1972,The Theory of Relativity, Clarendon Press, Oxford.
5. Soleng, H.: 1987a,Astrophys. Space Sci. 137, 403.