1. For reviews of the current situation see: a)R. J. Eden, P. V. Landsiioff, D. I. Olive andJ. C. Polkinghorne:The Analytic S-Matrix (Cambridge, 1966);
2. b)G. F. Chew:The Analytic S-Matrix (New York, 1966).
3. G. F. Chew:The Analytic S-Matrix (New York, 1966). AlsoG. F. Chew:Physics,1, 77 (1964).
4. A. O. Barut:Acta Phys. Austriaca Suppl. II, p. 162 (1966).
5. A. O. Barut andR. A. Blade:Nuovo Cimento,39, 331 (1965).