1. Cf.W. Heisenberg:An Introduction to the Unified Theory of Elementary Particles (London, 1967), German edition (Stuttgart, 1967).
2. H. Ezawa andJ. A. Swieca:Spontaneous breakdown of symmetries and zeromass states DESY-preprint 66/38, where previous literature is quoted.
3. R. F. Steater:Proc. Roy. Soc., A287, 510 (1965).
4. A. Licht:Ann. of Phys.,34, 161 (1965).
5. G. F. Dell’Antonio:Journ. Math. Phys.,2, 759 (1961);O. W. Greenberg:Ann. of Phys.,16, 158 (1961);R. Jost:The Generalized Theory of Quantized Fields (Providence, Rh. I., 1965).