1. P. K. Malhotra:Nucl. Phys.,46, 559 (1963).
2. A. Wroblewski:Proceedings of the III International Colloquium, on Multiparticle Reactions (Zakopane, 1972), p. 140.
3. For an up-to-date review, the reader is urged to consultA. Wroblewski:Proceedings of the X International Symposium on Multiparticle Dynamics (Goa, 1979), p. 191.
4. Z. Koba, H. B. Nielsen andP. Olesen:Nucl. Phys. B,40, 317 (1972).
5. A. Wroblewski:Acta Phys. Pol. B,4, 857 (1973);A. Buras, J. Dias de Deus andR. Møller:Phys. Lett. B,47, 251 (1973).