1. a) I. V. Terent'eva, in the collection: Alkaloid-Bearing Plants of Moldavia [in Russian], Kishinev, p. 21, 1960; b) P. A. Bember, I. V. Terent'eva, and G. V. Lazur'evskii, KhPS [Chemistry of Natural Compounds], 3, 249, 1967.
2. V. M. Chernov, in the collection: Alkaloid-Bearing Plants of Moldavia [in Russian], Kishinev, p. 49, 1960; M. D. Mashkovskii, Medicinal Substances [in Russian], Moscow, p. 88, 1964.
3. K. Mothes and H. R. Schutte, Angew. Chemie,75, 370, 1963.
4. E. Leete, J. Amer. Chem. Soc.,82, 6388, 1960.
5. E. Leete, A. Ahmad, and I. Kompis, J. Amer. Chem. Soc.,87, 4168, 1963.