1. Y. Nambu:Progr. Theor. Phys. (Kyoto),7, 595 (1952).
2. A good review of experimental tests of quantum electrodynamics is given byS. Drell: inAtomic Physics, edited byB. Bederson, V. Cohen andF. Pichanick (New York, 1969), p. 53.
3. M. H. Mac Gregor:Lett. Nuovo Cimento,4, 413, 1043 (1970).
4. M. H. Mac Gregor:Lett. Nuovo Cimento,4, 1309 (1970).
5. See, for example,L. B. Okun:Weak Interactions of Elementary Particles, Chap. 6 (London, 1965);J. Bernstein:Elementary Particles and Their Currents (San Francisco, 1968), p. 128.