1. S. A. Boguslavskij, The Paths of Electrons, in Selected Papers in Physics (Fizmatgiz, Moscow, 1961).
2. J. D. Jackson, Classical Electrodynamics (Wiley, New York, 1962).
3. N. A. Krall and A. W. Trivelpiece, Principles of Plasma Physics (McGraw-Hill, New York, 1973).
4. E. Kamke, Differentialgleichungen, Bd. I: Gewöhnliche Differentialgleichungen (Geest and Portig, Leipzig, 1959; Nauka, Moscow, 1976).
5. J. Zbornik, Z. Angew. Math. Phys. 7, 64 (1956).