1. A. Gordeev et al., Annals of the New York Academy of Sciences,251, 668 (1975).
2. E. Baranchikov et al., Int. Topical Conf. on Electron Beam Research and Technology, Albuquerque,1, 284 (Nov. 3?5, 1975).
3. L. Rudakov et al., Sixth European Conference on Controlled Fusion and Plasma Physics, Moscow,2, 430 (1973).
4. S. P. Bugaev et al., Usp. Fiz. Nauk,115, 101 (1975).
5. M. A. Blokhin, The Physics of X Rays [in Russian], Gostekhteorizdat, Moscow (1957).