1. Feynman, R. P. (1961).Quantum Electrodynamics, p. 142. Benjamin, New York.
2. Feynman, R. P. (1965).Lectures on Physics, Vol. I, pp. 2?6. Addison-Wesley, Reading, Mass.
3. M�ller, C. (1952).Theory of Relativity, p. 193. Oxford University Press, London.
4. Perl, M. L. et al. (1976).Physics Letters,63B, 117.
5. Rosen, G. (1971).Physical Review D,4, 275.