1. L. S. Gorn and B. I. Khazanov, Radiation Intensity Recorders [in Russian], Atomizdat, Moscow (1965).
2. N. N. Shumilovskii and L. V. Mel'ttser, Principles of the Theory of Automatic Monitoring Devices with the Use of Radioactive Isotopes [in Russian], Izd. Akad. Nauk SSSR, Moscow (1959).
3. U. Fano, Phys. Rev.,70 (1946);72 (1947).
4. J. R. Herring and E. J. Merzbacher, Elisha Mittchell Sci. Soc.,73 (1957).
5. S. C. Curran and A. L. Cockroft, J. Angus. Phil. Mag.,40, (1949).