Kovalev, B. G.; Dzhumakulov, T.; Abduvakhabov, A. A. Journal of Organic Chemistry USSR (English Translation), 1988 , vol. 24, # 10 p. 1909 - 1912 Zhurnal Organicheskoi Khimii, 1988 , vol. 24, # 10 p. 2116 - 2120