1. B. Desay:Phys. Rev.,119, 1385 (1960).
2. a)R. Armenteros, L. Montanet, D. R. O. Morrison, S. Nilsson, A. Shapira, J. Vandermeulen, Ch. d'Andliau, A. Astier, Ballam, C. Ghesquière, P. B. Gregory, D. Rahm, P. Rivet andF. Solmitz 1962 International Conference on High-Energy Physics at CERN, p. 351;b)G. B. Chadwick, W. T. Davies, M. Derrick, C. J. B. Hawkins, J. H. Mulvey, D. Radojicic, C. A. Wilkinson, M. Cresti, S. Limentani andR. Santangelo:Phys. Rev. Lett.,10, 62 (1963);c)C. Baltay, N. Barash, P. Franzini, N. Gel'fand, L. Kirsch, G. Lütjiens, D. Miller, J. C. Severiens, J, Steinberger, T. H. Tan, D. Tycko, D. Zanello, R. Goldberg andR. J. Plano:Phys. Rev. Lett.,15, 352 (1965).
3. D. Neville:Phys. Rev.,130, 327 (1963). We thank prof.R. Bizzarri for having called this fact to our attention.
4. R. Bizzarri andG. Snow: to be published.
5. A. Bettini, M. Cresti, S. Limentani, A. Loria, L. Peruzzo, R. Santangelo, L. Bertanza, A. Bigi, R. Carrara, R. Casali, E. Hart andP. Lariccia:Nuovo Cimento,42, 695 (1966).