1. H. Georgi:Conformal invariance cannot be broken by the vacuum, Yale preprint (1970).
2. See, for example,T. W. B. Kibble:Proceedings of the 1967 International Conference on Particles and Fields (New York, 1967), p. 277.
3. G. Mack:Nucl. Phys.,5 B, 499 (1968).
4. J. Strathdee andY. Takahashi:Nucl. Phys.,8, 113 (1958);Y. Takahashi:A note on the scale transformation, University of Alberta preprint (1970).
5. M. Gell-Mann:Lectures Delivered at the Summer School of Theoretical Particle Physics, University of Hawai (Honolulu, 1969).