Odinokov, V. N.; Kukovinets, O. S.; Kasradze, V. G.; Tsyglintseva, E. Yu.; Serebryakov, E. P.; Tolstikov, G. A. Chemistry of Natural Compounds, 1992 , vol. 28, # 1 p. 106 - 109 Khimiya Prirodnykh Soedinenii, 1992 , # 1 p. 125 - 129