1. Aachen-Berlin CERN-Cracow-London (I.C.)?Vienna-Warsaw collaboration IC/HENP/79/27 preprint, July (1980);
2. M. Basile et al.: CERN-EP/80-113 preprint June (1980);
3. P. V. Chliapnikov: Contribution to Bruge Symp. Belgium (1980);
4. W. Kittel: rapporteur's Review at the X Int. Symp. on multiparticles dynamics, GOA, September 1979
5. For a complete review on DTU see G. F. Chew, E. Rosenzweig: Phys. Rep.41, 263 (1978)