Odinokov, V. N.; Ishmuratov, G. Yu.; Ladenkova, I. M.; Muslukhov, R. R.; Tolstikov, G. A.
Chemistry of Natural Compounds, 1991 , vol. 27, # 2 p. 234 - 237
Khimiya Prirodnykh Soedinenii, 1991 , # 2 p. 272 - 276

Oehlschlager, Allan C.; Wong, John W.; Verigin, Victor G.; Pierce, Harold D.
Journal of Organic Chemistry, 1983 , vol. 48, # 25 p. 5009 - 5017