1. Allen, C. W.: 1977, Astrophysical Quantities, Moscow, Mir, p. 234.
2. Bisnovatyi-Kogan, G. S. and Ruzmaikin, A. A.: 1974, Astrophys. Space Sci. 28, 45.
3. Kobzarev, I. Yu., Okun, L. B., and Pomeranchuk, I. Ya.: 1966, J. Nucl. Phys. USSR 3, 1154.
4. Landau, L. D. and Lifshitz, E. M.: 1965, Mechanics, Moscow, Nauka, p. 55.
5. Lee, T. D. and Yang, C. N.: 1956, Phys. Rev. 104, 254.