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3. ?The Condensed Chemical Dictionary?, 8th Edn. (Van Nostrand Reinhold, New York, 1971).
4. Tu Chen, J. Crystal Growth 20 (1973) 29.
5. B. N. Litvin, L. N. Demyanets, L. S. Garshina, in ?Growth of crystals?, Vol. 4, edited by A. V. Shubnikov and N. N. Sheftal (Consultants Bureau, New York, 1966) p. 134.