1. Asahina, E., and Aoki, K., Nature, 182, 327 (1958).
2. Sakai, A., Low Temp. Sci., B, 14, 17 (1956).
3. Asahina, E., ibid., B, 16, 65 (1958).
4. Asahina, E., and Aoki, K., ibid., B, 16, 55 (1958).
5. Asahina, E., Contr. Inst. Low Temp. Sci., 10, 83 (1956).