1. For reviews see e.g.: J.R. Nix ? to be published in Progress in Particle and Nuclear Physics (1978) or Horst St�cker and Walter Greiner ? to be published in Phys. Rep. (1978)
2. Horst St�cker, J�rgen Hofmann, Werner Scheid and Walter Greiner: ? Proc of the Conf. on Nuclear Collisions, Bled (Yugoslavia), September 1977, ? Proc. of the Bormio Winter Meeting 1978, Bormio (Italy), January 1978.
3. Horst St�cker, Walter Greiner and Werner Scheid ? to be published.