1. See e.g. Kopal, Z. “Close binary systems” Chapman and Hall, London 1959 and References therein.
2. See e.g. Plavec, M. “Mass exchange and Evolution of Close binaries” in Advances in Astronomy and Astrophysics Vo.6-1968 and reference therein.
3. Giacconi, R., Ruffini, R.: “Physics and astrophysics of neutron stars and black holes”, Proc. International School “Enrico Fermi” (Varenna, Italy), 1978, North Holland, Amsterdam.
4. See e.g.: Bahcall, J.N.: 1978, Am. Rev. As. Ap. 16, 241.
5. Rhoades, C.E., Ruffini, R.: 1974, Phys. Rev. Lett. 32, 324.