1. V. Gilinsky, Phys. Rev.,137, 50 (1965).
2. Yu. A. Medvedev, B. M. Stepanov, and G. V. Fedorovich, Zh. Tekh. Fiz.,39, No. 5, 875 (1969).
3. W. Heitler, Quantum Theory of Radiation, Oxford, New York (1954).
4. K. Siegbahn (editor), Beta- and Gamma-Ray Spectroscopy, Interscience, New York (1955).
5. O. I. Leipunskii, B. V. Novozhilov, and V. N. Sakharov, Propagation of ?-Quanta in a Substance [in Russian], Fizmatgiz, Moscow (1960).