1. R. P. Feynman: inHigh-Energy Collisions, Third International Conference Held at State University of New York, Stony Brook, 1969, edited byC. N. Yang et al. (New York, 1969).
2. J. D. Bjorken andE. H. Paschos:Phys. Rev. 185, 1975 (1969).
3. J. D. Bjorken:Phys. Rev.,179, 1547 (1969).
4. G. Miller, E. D. Bloom, G. Buschhorn, D. H. Coward, H. DeStaebler, J. Drees, C. L. Jordan, L. W. Mo, R. E. Taylor, J. I. Friedman, G. C. Hartmann, H. W. Kendall andR. Verdier:Phys. Rev. D,5, 528 (1972).
5. A review is given byR. A. Brandt andG. Preparata: inProceedings of the 1971 Hamburg Summer School, to be published inSpringer Tracts in Modern Physics.