1. See, for example,P. Collins andE. Squires:Regge Poles in Particle Physics (Berlin, 1968), and references therein.
2. SeeH. Kendall: inProceedings of the 1971 International Symposium on Electron and Photon Interactions at High Energies, edited byN. Mistry (Ithaca, N. Y., 1972), and references therein.
3. J. D. Bjorken:Phys. Rev.,179, 1547 (1969).
4. R. A. Brandt:Phys. Rev. Lett.,22, 1149 (1969);23, 1260 (1969);Phys. Rev. D,1, 2808 (1970).
5. For a review, seeR. A. Brandt: CERN preprint TH-1557, to appear inProceedings of the 1972 Erice Summer School.