1. Yu. S. Deev et al., At. Energ.,29, 303 (1970).
2. V. I. Spitsyn and V. V. Gromov, Physicochemical Properties of Radioactive Solids [in Russian], Atomizdat, Moscow (1973), p. 93.
3. H. Lackner, I. Kohlberg, and S. Nablo, J. Appl. Phys.,36, 2064 (1965).
4. O. B. Evdokimov and N. I. Yagushkin, Fiz. Tverd. Tela,16, 564 (1974).
5. B. Gross and S. Nablo, J. Appl. Phys.,38, 2272 (1967).