1. K. Siegbahn, Beta and Gamma Spectroscopy [Russian translation] (Fizmatgiz, Moscow, 1959).
2. B. Dzhelepov and L. Zyryanova, The Effect of the Electric Field of the Atom on Beta Disintegration [in Russian], (Izd. AN SSSR, Moscow, 1956).
3. G. Hine and G. Brownell, Radiation Dosimetry [Russian translation] (IL, Moscow, 1958).
4. W. Bragg, Studies in Radioactivity (New York, 1912).
5. L. Gray, Brit. J. Radiol.,10, 600, 721 (1937).