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2. Ann. Physik. 138, 280, 370 (1869).
3. F. Kohlrausch, L. Holborn, and H. Dieselhorst,Wied. Ann. 64, 425 (1898).
4. H. C. Parker and E. W. Parker,J. Am. Chem. Soc. 46, 312 (1924).
5. International Critical Table, VI, 230, McGraw-Hill Book Co., New York, 1929.