1. J. C. Pati and Abdus Salam, Phys. Rev. D8, 1240 (1973);
2. J. C. Pati and Abdus Salam, Phys. Rev. Letters 31, 661 (1973);
3. J. C. Pati and Abdus Salam, Phys. Rev. D10, 275 (1974).
4. Of course, some day the theory must also explain what determines the characteristic energy at which the distinction between weak and electromagnetic forces disappears on the one hand and strong and weak and electromagnetic on the other.
5. S. Brodsky and J. Sapirstein, (to be published).