1. See e.g. A. Bertin, A. Vitale, and A. Placci, La Rivista del Nuovo Cimento 5:423 (1975); and references therein.
2. L.I. Ponomarev, L.N. Romov, and N.P.Faifman, JINR preprint P4-11446 (1978); and references therein.
3. See e.g. A. Vitale, A. Bertin, and G. Carboni, Phys. Rev. 11D: 2441 (1975); and references therein.
4. V.P. Dzhelepov, P.F. Ermolov, and V.V. Fil’chenkov, Zurn. EKsp. Teor. Fiz. 49:393 (1965)(English translation: Sov. Phys. JETP 22:275 (1966)).
5. A. Alberigi Quaranta, A. Bertin, G. fiatone, F. Palmonari, A. Placci, P. Dalpiaz, G. Torelli, and E. Zavattini, Nuovo Cimento 47 B: 72 (1967).