Shapovalov, A. A.; Zhalgasbaeva, G. Sh.; Sembaev, D. Kh.; Suvorov, B. V. Journal of Organic Chemistry USSR (English Translation), 1987 , vol. 23, # 6 p. 1140 - 1143 Zhurnal Organicheskoi Khimii, 1987 , vol. 23, # 6 p. 1260 - 1264