1. S.Y. Lo, D.J. Clarke and M.M. Malone, Proceedings of 1980 Guangzhon Conference on Theoretical Particle Physics, p. 813 (1980);
2. D.J. Clarke and S.Y. Lo, Phys. Rev. D20, 193 (1979); ibid. Phys. Lett. 87B, 379 (1979); ibid. "Spin Effects and Energy Dependence of Proton-Proton Elastic Scattering", University of Melbourne preprint UM-P-81/15, and references therein.
3. T.T. Chou and C.N. Yang, Phys. Rev. 170, 1591 (1968).
4. T.T. Chou and C.N. Yang, Rev. Lett. 20, 1213 (1968).
5. 2. M. Kac, Nucl. Phys. B62, 402 (1973)