1. R.F. Streater and A.S. Wightman, “PCT, Spin & Statistics, and all that,” Benjamin, New York, 1964, S.S. Schweber, Introduction to Relativistic Quantum Field Theory, Row, Peterson and Co., Evanston, Illinois (1961).
2. D. Ruelle, Helv. Phys. Acta 35: 147 (1962); cf. also: R. Jost, “The General Theory of Quantized Fields,” American Mathematical Society, Providence, Rhode Island (1965).
3. K. Hepp, Helv. Phys. Acta 37: 639 (1964).
4. J. Bros, H. Epstein, and V. Glaser, Nuovo Cimento 31: 1265 (1964).
5. S. Mandelstam, Nuovo Cimento 15: 658 (1960).