1. For a review, seeH. Lipkin:Quarks for pedestrians, inLecture Notes at Weizmann Institute (unpublished).
2. R. Gatto, L. Maiani andG. Preparata:Physics,3, 1 (1967);N. Cabibbo andH. Ruegg:Phys. Lett.,22, 85 (1966).
3. For a phenomenological review on (L=1) meson production seeG. C. Fox: inPhenomenology in Particle Physics, edited byC. B. Chiu, G. C. Fox andA. Hey (Pasadena, Cal., 1971);C. Michael: preprint CERN TH. 1567 (1972).
4. F. Buccella, H. Kleinert, C. A. Savoy, E. Celeghini andE. Sorace:Nuovo Cimento,69 A, 133 (1970).