1. Aldersley, S. J. (1977).Gen. Rel. Grav.,8, 397.
2. Anderson, J. L. (1967).Principles of Relativity Physics (Academic Press, New York).
3. Davis, W. R. (1970).Classical Fields, Particles, and the Theory of Relativity (Gordon and Breach, New York).
4. Einstein, A. (1916).Sitzungsber. Preuss. Akad. Wiss. (Berlin), p. 1111.
5. Einstein, A. (1925).Sitzungsber. Preuss. Akad. Wiss. (Berlin), p. 414.