1. J. M. Müller, E. Schlittler, andH. J. Bein, Exper.8, 338 (1952).
2. R. B. Woodward, F. E. Bader, H. Bickel, A. J. Frey, andR. W. Kiersted, Tetrahedron2, 1 (1958).
3. For the use of these terms seeR. Robinson,The Structural Relations of Natural Products (Oxford at the Clarendon Press, 1955), p. 100.
4. By an X-ray method,A. F. Peerdeman, Acta cryst.9, 824 (1956). No chemical proof is yet available.
5. A. K. Bose, B. G. Chatterjee, andR. S. Iyer, Ind. J. Pharm.18, 185 (1956)