1. MARK II Coll. M.W. Eaton et al.: Phys. Rev.D 29, 804 (1984)
2. MARK III Coll.: Talk at ?XXIII International Conference on High Energy Physics?, Berkeley 1986
3. DM2 Coll.: Talk at ?XXIII International Conference on High Energy Physics?, Berkeley 1986
4. J.G. Körner, M. Kuroda: Phys. Rev.D 16, 2165 (1977)
5. J.G. Körner, in: Proceedings of the Third LEAR Workshop, Tignes 1985. Gif-sur-Yvette: Editions Frontieres 1985