1. SeeA. B. Clegg: inProceedings of the IV International Symposium on Electron and Photon Interactions at High Energies (Liverpool, 1969), p. 123, and references quoted there.
2. SeeF. Gutbrod: inProceedings of the IV International Symposium on Electron and Proton Interactions at High Energies (Liverpool, 1969), p. 141, and references quoted there.
3. P. Kessler:Nuovo Cimento,40 A, 887 (1965); see alsoA. Bhattacharya andP. Kessler:Compt. Rend.,259, 310 (1964).
4. G. Cochard andP. Kessler:Lett. Nuovo Cimento,2, 363 (1969);4, 1191 (1970).