1. K. Johnson andF. E. Low:Progr. Theor. Phys., to be published.
2. B. Hamprecht:Nuovo Cimento,50 A, 449 (1967).
3. For a summary see Chapter III ofThe Analytic S-Matrix,R. J. Eden, P. V. Landshoff, D. I. Olive andJ. C. Polkinghorne (Cambridge, 1966).
4. J. D. Bjorken:Phys. Rev.,148, 1467 (1966).
5. E. Y. C. Lu:Nuovo Cimento,49 A, 136 (1967).