1. M. Gell-Mann:Phys. Lett.,8, 274 (1964);,G. Zweig: Cern preprint. 8479/TH 472 (1964).
2. Excellent reviews are:R. H. Dalitz:Quark Models for the Elementary Particles, Lectures given at Les Houches (1965);
3. R. H. Dalitz: Invited paper presented at theOxford International Conference (Oxford, Sept. 1965);H. Thirring:Acta Phys. Austriaca, Suppl. III,3, 294 (1966).
4. N. N. Bogoliubov,et al.: Dubna Report D-1968 (1965), P-2569 (1966);
5. H. J. Lipkin andA. Tavkhelidse:Phys. Lett.,17, 331 (1965).