1. N. N. Bogoliubov andD. V. Shirkov:Introduction to the Theory of Quantized Fields (New York, 1959);S. Schweber:An Introduction to Relativistic Quantum Theory (Evanston, Ill., 1961);J. D. Bjorken andS. D. Drell:Relativistic Quantum Fields (New York, 1965).
2. F. A. Berezin:The Methods of Second Quantization (1966).
3. E. R. Caianiello, F. Guerra andM. Marinaro:Nuovo Cimento,60 A, 713 (1969);M. Marinaro:Nuovo Cimento,9 A, 62 (1972);E. R. Caianiello:Combinatorics and renormalization in quantum field theory, in press,Frontiers in Physics (New York).
4. J. G. Valatin:Proc. Roy. Soc.,222, 93 (1954);225, 535 (1954);226, 254 (1954);W. Zimmermann:Comm. Math. Phys.,6, 161 (1967).
5. T. D. Lee:Phys. Rev.,95, 1329 (1954);F. Y. Yndurain:Journ. Math. Phys.,7, 1133 (1966);9, 1423 (1968);F. Guerra:Nuovo Cimento,68 A, 258 (1970).