1. I. E. Konstantinov, Collection, ?Some Engineering Physics Problems? [in Russian], Moscow, Izd. MIFI, 1958, p. 32.
2. R. Carr and J. Lamkin, Phys. Rev.,75, 467 (1949).
3. H. Goldstein and J. Wilkins, US AEC, report NYOO-3075 (1954).
4. D. P. Osanov and E. E. Kovalev, ?Atomnaya Énergiya?,8, No. 4, 374 (1960).