1. See e.g.: Proceedings of Quark Matter '88, Nucl. Phys. A498 (1989)
2. See e.g.: M.Gyulassy: Nucl. Phys. A 418 (1985) 559c, and references given there
3. R. Albrecht et al. (WA 80): Upper Limit for Thermal Direct Photon Production in Heavy Ion Collisions at 60 and 200A-GeV, Preprint CERN-PPE/91-01, 1991
4. See e.g., V. Ruuskanen, in: Proceedings of the VIIIth International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Menton/France, 1990; Nucl. Phys. A, in press
5. T. Matsui, H. Satz: Phys. Lett. 178B (1986) 416