1. Bennet, A. S.: 1962,Mem. Roy. Astron. Soc. 68, 163.
2. Braude, S. Ya., Ryabov, B. P., and Zhouck, I. N.: 1971,Astrophys. Space Sci. 12, 349.
3. Ginzburg, V. L. and Syrovatski, S. I.: 1963,The Origin of Cosmic Rays (in Russian), AN SSSR Publishers, Moscow.
4. Gnedin, Yu. N., Dolginov, A. Z., and Fedorenko, V. N.: 1972,Pis'ma v Zh.E.T.F. (Sov. Phys.-JETP Letters) 16, 45.
5. Kaplan, S. A. and Pikel'ner, S. B.: 1963,Interstellar Medium (in Russian), FMG, Moscow.