1. Z. Koba, H. B. Nielsen andP. Olesen:Nucl. Phys.,40 B, 317 (1972);Phys. Norvegica,5, 303 (1971).
2. P. Olesen: Niels Bohr Institute preprint, NBI-HE-72-10.
3. P. Slattery: COO-3065-26, UR-409:a) The data relative to 50and 69 GeV/cincident momenta are taken in the Mirabelle chamber at Serpukhov, Soviet-French Collaboration:Contribution submitted to the XVI International Conference on High-Energy Physics;b) The data relative to 102, 205and 303 GeV/oincident momenta are taken in the NAL/ANL 30 inch chamber at NAL. (102 GeV/c)J. W. Chapman et al.: COO-3065-23, UR-395, UMBC-72-11; (205 GeV/c)G. Charlton et al.: Phys. Rev. Lett.,29, 515 (1972); (303 GeV/c)F. T. Dao et al.: NAL-UCLA, NAL-78, 7200-037.
4. H. B. Nielsen andP. Olesen: Niels Bohr Institute preprint (NBI-HE-72-12).
5. R. P. Feynman:High-Energy Collisions, Stony Brook Conference (1969);