1. C. N. Yang and R. L. Mills:Phys. Rev.,96, 191 (1954).
2. R. Utiyama:Phys. Rev.,101, 1597 (1956).
3. See, for example, J. Bernstein:Rev. Mod. Phys.,46, 7 (1974).
4. See, for example,S. Gasiorowicz:Elementary Particle Physics, Chap.18 (New York, N. Y., 1966).
5. See,e.g.,W. R. Fraser:Elementary Particles, subsect. 88 (New Jersey, 1966). Also Betrnstein, ref. (7), sect.7.