1. Feldman, G.: Rapporteur talk at the XIX International Conference on High Energy Physics, Tokyo, 1978
2. Berkov, A.V., Khoze, V.A., Nikitin, Yu.P., Zhizhin, E.D.: Zh. Exp. Teor. Fiz.73, 1644 (1977)
3. Gaemers, K., Raitio, R.: Phys. Rev.D14, 1962 (1976)
4. Azimov, Ya. I., Frankfurt, L.L., Khoze, V.A.: Zh. Exp. Teor Fiz,72, 63 (1977)
5. Here we do not take into account the widths of the intermediate cascade states, which can be done in the standard way as in [2] and [3]