1. R. J. Esterling, N. E. Booth, G. Conforto, J. Parry, J. Scheid, D. Sherden andA. Yokosawa:Phys. Rev. Lett.,21, 1410 (1968):P lab=5.15 GeV/c;M. Borghini, G. Coignet, L. Dick, L. Di Lella, A. Michalowicz, P. C. Macq andJ. C. Olivier:Phys. Lett.,21, 114 (1966);24 B, 77 (1967);31 B, 405 (1970):P lab=6.0, 10.0, 12.0 GeV/c.
2. See, for instance,J. D. Jackson:Proceedings of the Lund International Conference on Elementary Particles (1969), p. 61, and references therein.
3. G. Berlad, A. Dar andG. Eilam: Technion preprint (unpublished). The main difference between the above paper and the present paper is the introduction of a phase consistent with analyticity and crossing.
4. A. Dar:Proceedings of the III International Conference on High-Energy Physics and Nuclear Structure (Columbia, 1969), p. 832; see also:H. Harari:IV International Symposium on Electron and Photon Internactions at High Energies (Liverpool, 1969), p. 107;A. Dar: invited talk at theV Rencontre de Moriond, Meribel-les-Allues, 1970 (Technion preprint).
5. P. G. O. Freund:Phys. Rev. Lett.,20, 235 (1968);H. Harari:Phys. Rev. Lett.,20, 1395 (1968).