1. See e.g.A. N. Diddens, Rapporteur talk at the XVIIth International Conference on High Energy Physics, London, 1974, Proceedings, p. 1–41.
2. I. Ja. Pomeranchuk, ZhETF,34, 725, 1958.
3. G. Grunberg andT. N. Truong, Phys. Rev. Letters,31, 63, 1973.
4. See e.g.N. M. Queen, Fortschr. d. Physik,17, 467, 1969.
5. A. Martin, Proc. 8eme Renc. de Moriond, 1973, p. 91.