1. Bateman, H. and Erdélyi, A.: 1953,Higher Transcendental Functions, Vol. 2, McGraw-Hill Book Co., New York.
2. Bulanov, S. V. and Dogiel, V. A.: 1975,Proc. XIVth Intern. Conf. on Cosmic Rays, Münich 2, 706.
3. Bulanov, S. V. and Dogiel, V. A.: 1979,Izv. AN SSSR, Ser. Fiz. 43, 2474 (in Russian).
4. Carvalho, J. C. and ter Haar, D.: 1979,Astrophys. Space Sci. 61, 45.
5. Getmantsev, G. G.: 1952,Dokl. Akad. Nauk SSSR 83, 557 (in Russian).