1. A. Tchitchibabine, Pat. Fr. 769216.
2. A. Tchitchibabine, M. Bestougeff, Comp. Rend., 1935, 200, 342.
3. M. Repas, V. Macho, J. E. Mistrik, Chem. Zvesti, 1966, 20, 501; Chem. Abstr., 1966, 65, 15181.
4. F. Berbe, Bull. Soc. Chim. Belg., 1950, 59, 449.
5. A. D. Malievskii, Dokl. Akad. Nauk SSSR, 1970, 190, 884 (in Russian).