1. Chatterjee, S. K., Ind. Ceram.2, (6), 117 (1955).
2. Dana, E. S., Textbook of Mineralogy. W. E. Ford (New York 1921).
3. DeWit, C. P. andP. L. Arens, Trans. 4th. Intern. Congr. Soil Sci.2, 59 (1950).
4. Hauser, E. A. andD. S. Le Beau, J. Phys. Chem.42, 1031 (1938). ibid.45, 54 (1941).
5. Hofmann, U., Kolloid-Z.169, 58 (1960).