1. T. D. Lee andC. N. Yang:Phys. Rev.,104, 254 (1956).
2. A. Salam:Nuovo Cimento,5, 299 (1957).
3. L. D. Landau:Žurn. Ėksp. Teor. Fiz.,32, 405 (1957).
4. T. D. Lee andC. N. Yang:Phys. Rev.,105, 1671 (1957).
5. For a recent review seeS. Ferrara:Supersymmetric theories of fundamental interactions, inThe New Aspects of Subnuclear Physics, Proceedings of the «Ettore Majorana» International School of Subnuclear Physics, Erice, 1978, in press. See also CERN. TH-2514 (1978).