1. W. H. Zachariasen, J. Chem. Phys. 5, 919 (1937); Kristallogr. 88, 150 (1934); 78, 289 (1931).
2. A. V. Nikolaev, Physicochemical Study of Natural Borates (Acad. Sci. USSR Press, Moscow and Leningrad, 1947),
3. N. Basset, Theory of Quantitative Analysis (State United Sci. Tech. Press, 1932), p. 212.
4. L. Cambi, C. 1914, I, 1412.
5. A. I. Shatenshtein, Theory of Acids and Bases (State Chem. Press, Moscow 1949); p. 231.