1. Curry, M.A., Legvold, S., Spedding, F.H.: Phys. Rev. 117 (1960) 953.
2. Bridgman, P.W.: Collected Experimental Papers, Vol. VII, Cambridge: Harvard Univ. Press 1964, p. 4323.
3. Legvold, S., Beaver, J.P.: Solid State Commun. 31 (1979) 727.
4. Kadomatsu, H., Nishida, T., Tsutaoka, T., Fujiwara, H.: J. Phys. Soc. Jpn. 56 (1987) 2902.
5. Nishida, T., Kadomatsu, H., Fujiwara, H.: J. Phys. Soc. Jpn. 56 (1987) 2896.