1. J. Baacke, Acta Phys. Pol. B 8, 625 (1977)
2. This fact is known already to cosmic ray physicists and has been stated in so many papers that it is impossible to list them all. Let two more recent ones represent the whole lot:(a) A.T. Laasanen, C. Ezell, L.J. Gutay, W.N. Schreiner, P. Schübelin, L. von Lindern, F. Turkot, Phys. Rev. Lett. 38, 1 (1977);
3. (b) G.W. van Appeldoorn, S. Barshay, D. Harting, D.J. Holthuizen, P.G. Kuijer, B.J. Pijlgroms, V. Karimäki, R. Kinnunen, M. Korkea-Aho, P. Johnson, D. Michaelides, Ch. Michaelidou, D.G. Patel, Z. Physik C, Part. Fields 7, 235 (1981)
4. We do not consider here Monte Carlo lattice calculations which may indeed cover both sides and do suggest a phase transition, but which cannot exhibit singularities in the strict sense. See, e.g., J. Engels, F. Karsch, I. Montvay, H. Satz, Phys. Lett. B 102, 332 (1981) and references therein
5. (a) R. Hagedorn, J. Rafelski, Phys. Lett. B 97, 136 (1980);