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2. M. Ushio, H. Saito and S. Nagano, ibid 74 (1971) 598.
3. O. Fukunaga, T. Sato, M. Iwata and H. Hiraoka, Proceedings of the 4th International Conference on High Pressure, Kyoto (1974) p. 454.
4. T. Endo, O. Fukunaga and M. Iwata, J. Mater. Sci. (to be published).
5. H. T. Hall, Rev. Sci. Instrum. 31 (1960) 125.