1. See, for example, D. Benderet al., Phys. Rev. D30, 515 (1984), p. 521.
2. M. H. Mac Gregor,Phys. Rev. D9, 1259 (1974), App. B;The Nature of the Elementary Particle (Springer, Heidelberg, 1978), Chaps. 6 and 7.
3. M. H. Mac Gregor,Lett. Nuovo Cimento 43, 49 (1985) and44, 697 (1985);Found. Phys. Lett. 1, 25 (1988) and2, 577 (1989).
4. J. L. Synge and B. A. Griffith,Principles of Mechanics (McGraw-Hill, New York, 1942), p. 349.
5. V. Spiegelet al., Ann. Phys. 6, 70 (1959).