1. K. Kimoto, Y. Kamiya, M. Nonoyama, and R. Uyeda, Jpn. J. Appl. Phys. 2, 702 (1963).JJAPA50021-4922
2. N. Wada, Jpn. J. Appl. Phys. 6, 553 (1967).JJAPA50021-4922
3. K. Kimoto and I. Nishida, Jpn. J. Appl. Phys. 6, 1047 (1967).JJAPA50021-4922
4. N. Wada, Jpn. J. Appl. Phys. 7, 1287 (1968).JJAPA50021-4922
5. I. Nishida, J. Phys. Soc. Jpn. 26, 1225 (1969).JUPSAU0031-9015