1. Kanamaru, K., Chao, J.: J. Soc. chew. Industr. Japan41, 171 (1938); ref. Chem. Abstr.39, 9483 (1938)
2. Lauer, K.: Kolloid-Z.107, 86 (1944).
3. Cassidy, H. G.: Anal. Chem.24, 1415 (1952).
4. Benson, S. W., Seehof, J. M.: J. Am. Chem. Soc.75, 3925 (1953).
5. Rudi, V. P., Morozov, A. A.: Vestsi Akad. Navuk Belarus. SSR, Ser. Fiz.-Tekh. Navuk1956, 111; ref. Abstr.51, 13 520 (1957).