Yuldashev, M. P.; Batirov, E. Kh.; Vdovin, A. D.; Malikov, V. M.; Yagudaev, M. R. Chemistry of Natural Compounds, 1989 , vol. 25, p. 303 - 308 Khimiya Prirodnykh Soedinenii, 1989 , # 3 p. 352 - 359