1. A. M. Afanas’ev and V. G. Kon, Zh. Éksp. Teor. Fiz. 74, 300 (1978) [Sov. Phys. JETP 47, 154 (1978)].
2. A. A. Dyshekov and Yu. P. Khapachev, Poverkhnost’ No. 3, (1997).
3. A. A. Dyshekov and Yu. P. Khapachev, Poverkhnost’ No. 3, (1997).
4. A.-H. Nayfeh, Perturbation Methods [Wiley, New York (1973); Mir, Moscow (1976), 455 pp.].
5. Handbook of Mathematical Functions, edited by M. Abramowitz and I. A. Stegun [Dover, New York (1965); Nauka, Moscow (1979), 832 pp.].