1. See for instance,R. H. Dalitz:Proc. of the Oxford International Conference on Elementary Particles (1965), p. 159;R. Gatto, L. Maiani andG. Preparata:Phys. Rev.,140, B 1579 (1965);
2. C. Nwachuku:Nuovo Cimento,45 A, 58 (1966);
3. O. Sinanoglu:Phys. Rev.,145, 1205 (1966).
4. See, for instance,A. Salam:Proc. of the Oxford International Conference on Elementary Particles (1965), p. 241;A. Salam andJ. Strathdee:Reggeization of internal symmetries, to be published inPhys. Rev. Lett.; ICTP, Trieste, preprint IC/67/39 (1967);
5. C. Fronsdal andR. White:Phys. Rev.,151, 1287 (1966);