1. B. Richter: talk presented at theSeminar on e+e-Colliding Beam Physics, held at Trieste (June 1974).
2. R. P. Feynman:Photon-Hadron Interactions (New York, N. Y., 1972);M. Gronau, F. Ravndal andY. Zarmi:Nucl. Phys.,51 B, 611 (1973).
3. J. T. Dakin, G. J. Feldman, F. Martin, M. L. Perl andW. T. Toner: SLAC-PUB-1421 (to be published inPhys. Rev.).
4. F. J. Gilman: talk presented at theLondon Conference (July 1974).
5. V. N. Gribov andL. N. Lipatov:Phys. Lett.,37 B, 78 (1971);Sov. Journ. Nucl. Phys.,15, 438, 672 (1972).