1. For a good account of “Cabibbo” weak interaction theory (before the discovery of neutral weak currents, etc.) see E.D. Commins, in Weak Interactions (McGraw-Hill, New York, 1973)
2. M. Gari, Phys. Rep. 6C (1973) 319
3. For example see H. Fritzsch and P. Minkowski, Phys. Lett. to be published
4. S. Weinberg, Phys. Rev. Letts. 19 (1967) 1264; 27 (1971) 1688
5. A. Salam, in Elementary Particle Theory (Nobel Symposium No. 8)ed. N. Sìrartho]m ( John Wiley, New York, 1969 )