1. S.L. Glashow, J. Iliopoulos, L. Maiani: Phys. Rev. D2, 1285 (1970)
2. M.K. Gaillard, B.W. Lee, J.L. Rosner: Rev. Mod. Phys.47, 277 (1975)
3. A. Barbaro Galtieri: LBL-8537, Erice lectures (1978) and [35]
4. C. Baltay: in Proceedings of the 19th International Conference on High Energy Physics, Tokyo 1978, eds. S. Homma, M. Kawaguchi, H. Myazawa. Physical Society of Japan, 1978
5. Proceedings of the 19th International Conference on High Energy Physics, Tokyo 1978, especially G. Diambrini-Palazzi, and A. Kemp