1. U. Eisner and J. Kuthan,Chem. Rev.,72, 1 (1972).
2. A. A. Bakibaev and V. D. Filimonov,Zh. Org. Khim.,27, 854 (1991).
3. A. A. Bakibaev and V. D. Filimonov,Zh. Org. Khim.,27, 859 (1991).
4. G. Ya. Vanag and E. I. Stankevich,Zh. Obshch. Khim.,30, 3287 (1960).
5. E. I. Stankevich and G. Ya. Vanag,Izv. Akad. Nauk Latv. SSRR, Ser. Khim., No. 3, 223 (1961).