1. Akhmedov, S. G. and Litvinenko, V. I. (1969), Chem. Natural Comp.
5, Engl. Trans., 47.
2. Aknin, J. and Molho, D. (1963), Bull. Soc. chim. France 604.
3. Anjaneyulu, B. and Govindachari, T. R. (1969), Tetrahedron Letters 2847.
4. ApSimon, J. W., Haynes, N. B., Sim, K. Y. and Whalley, W. B. (1963), J. chem. Soc. 3780.
5. Arisawa, M., Takakuwa, T. and Nakaoki, T. (1970), Chem. pharm. Bull
18, 916.