1. See e.g. J.N. Bahcall, Rev. Mod. Phys.,50, 881, 1978.
2. R. Davies, Proc. Underground Physics, Baksan, USSR, 1987. ed. by Y. Zatsepin, Moscow, 1988.
3. See the review of G. Marx, in “Sun and Planetary Systems”, ed. by W. Fricke and G. Teleki, D. Reidel, New York, 1982.
4. G. Marx and N. Menyhárd, Mitteilungen der Sternwarte Budapest, 44, 1960.
5. E.L. Pollock and B.J. Adler, Nature,275, 41, 1978.