1. M. F. Shostakovsky and A. V. Bogdanova, J. Gen. Chem. 21, 631 (1951).
2. M. F. Shostakovsky and A. V. Bogdanova, J. Gen. Chem. 17, 565 (1947); 20, 1315 (1950).
3. W. Cocker, A. Lapworth, A. Walter, J. Chem. Soc. 1930, 440.
4. J. Allard, Bull. Soc. Chim, France 7, 751 (1947).
5. I. S. Simkhaev and I. P. Tsukervanik, Bull. Acad. Sci. UzbekSSR, No. 4, 28 (1948).