1. See, for, example:S. Coleman:Secret symmetry: an introduction to spontaneous symmetry break-down and gauge fields (Erice, 1973), and references quoted therein.
2. E. R. Caianiello andG. Scarpetta:Nuovo Cimento,22 A, 448 (1974);Lett. Nuovo Cimento,11, 283 (1974).
3. J. R. Klauder:On model fields with indipendent values at every space-time point, preprint, Bell Laboratories.
4. E. R. Caianiello:Nuovo Cimento,10, 1634 (1953);11, 492 (1954);E. R. Caianiello, F. Guerra andM. Marinaro:Nuovo Cimento,60 A, 713 (1969);E. R. Caianiello:Combinatorics and Renormalization in Quantum Field Theory (New York, N. Y., 1974).
5. K. Symanzik:Rendiconti S.I.F., Course XLV, edited byR. Jost (New York, N. Y., and London, 1969).