1. For a recent review seeR. Delbourgo, M. A. Rashid, A. Salam andJ. Strathdee: The $$\tilde U_{12} $$ Symmetry, IC/65/57 (Trieste), to be published in theProceedings of the Seminar on High-Energy Physics and Elementary Particles, Trieste, 1965 (IAEA, Vienna).
2. H. Harari andM. A. Rashid: preprint.
3. M. Gell-Mann:Phys. Rev.,125, 1067 (1962);S. Okubo:Progr. Theor. Phys.,27, 949 (1962).
4. This difficulty has been discussed in ref. (2).H. Harari andM. A. Rashid: preprint.
5. The particle symbols etc. denote squared masses.