Kayukova, L. A.; Chernova, N. V.; Manchuk, Z. N.; Erzhanov, K. B. Journal of Organic Chemistry USSR (English Translation), 1990 , vol. 26, # 8.1 p. 1389 - 1392 Zhurnal Organicheskoi Khimii, 1990 , vol. 26, # 8 p. 1608 - 1612