1. S. Hayakawa, Cosmis Ray Physics (Wiley, New York, 1969; Mir, Moscow, 1973), Part 1.
2. V, S. Berezinskii et al., The Astrophysics of Cosmic Rays, Ed. by V. L. Ginzburg (Nauka, Moscow, 1990) [in Russian].
3. M. Nagano and A. A. Watson, Rev. Mod. Phys. 72, 689 (2000).
4. V. A. Chechin et al., Nucl. Phys. B (Proc. Suppl.) 113, 111 (2003).
5. Physics of Cosmos. Small Encyclopedia (Sov. Entsiklopediya, Moscow, 1986) [in Russian].