1. L. Motz:Phys. Rev.,119, 1102 (1960).
2. L. Motz:Phys. Rev.,89, 60 (1953).
3. B. Kursunoglu:Private communication and report on relativity and gravitation. (Royaumont, June 1959);Nuovo Cimento,17, 729 (1960).
4. For a detailed discussion of this point seeA. S. Eddington:Fundamental Theory (Cambridge, 1946), p. 236.
5. A. S. Eddington:The Mathematical Theory of Relativity (Cambridge, 1923), p. 204.