1. B. B. Kadomtsev, Collective Phenomena in Plasmas, Pergamon Press, Oxford (1980).
2. V. V. Zheleznyakov, Electromagnetic Waves in Cosmic Plasma [in Russian], Nauka, Moscow (1977).
3. A. V. Gaponov, M. I. Petelin, and V. K. Ulpatov, Izv. Vyssh. Uchebn. Zaved. Radiofiz. 10, 1414 (1967).
4. F. Hopf, T. Cooper, D. Moore, and M. Scully, in Free-Electron Generators of Coherent Radiation [in Russian], A. A. Rukhadze (ed.), Mir Publishers, Moscow (1983) [Russian translation of a collection of papers on free-electron lasers].
5. A. V. Gaponov-Grekhov and M. I. Petelin, in Science and Mankind [in Russian], Znanie, Moscow (1980), p. 283.