1. Much of these lectures are also presented in the 1973 Proceedings of the Summer Institute on Particle Physics, edited by M. Zipf, SLAC-167 (1973).
2. R. P. Feynman, Photon-Hadron Interactions (W. A. Benjamin, New York, 1972).
3. J. Bjorken and J. Kogut, Phys. Rev. D 8, 1341 (1973).
4. S. Drell and T. Yan, Phys. Rev. Letters 24, 181 (1970).
5. G. West, Phys. Rev. Letters 24, 1206 (1970).