Mikhail E. Prokhorov and Konstantin A. Postnov
Sternberg Astronomical Institute, 119899 Moscow, Russia.
E-mail: snn@sai.msk.su (INTERNET)
The paper is a revised version of the talk
given at the 2-nd Seminar
``Physics of Neutron Stars''
Sanct-Peterburg, March 16-19 1992.