1. S. B. Hendricks, E. Posnjak, F. C. Kracek, J. Am. Chem. Soc. 54, 2784 (1932).
2. J. L. Crenshaw, J. Ritter, Z. phys. Chem., 16, 148 (1932).
3. P. G. Meerman, Rec. trav. pay, 60, 363 (1941).
4. J. Jaffray, Ann. phys. 3, 70 (1948).
5. H. Volkringer, M Freymann, R. Freymann, Compt. rend. 208, 1005 (1939).