1. V. S. Berezinsky et al. Astrophysics of Cosmic Rays, Ed. by V. L. Ginzburg, 2nd ed. (Nauka, Moscow, 1990; North-Holland, Amsterdam, 1990).
2. J. P. Rachen and P. L. Biermann, Astron. Astrophys. 272, 161 (1993).
3. V. Berezinsky, A. Z. Gazizov, and S. I. Grigorieva, hepph/0204357.
4. M. Takeda et al. (AGASA Collab.), Astrophys. J. 522, 225 (1999).
5. P. G. Tinyakov and I. I. Tkachev, Pis’ma Zh. Éksp. Teor. Fiz. 74, 3 (2001) [JETP Lett. 74, 1 (2001)].