1. See, for example, Natural Products. Academic Press London (1969).
2. See, for example, (a) (Ed), Studies for Natural Products, Vol. 6, Stereoselective Synthesis (Part D), Elsevier, Amsterdam, 1990;
3. (b) Enantioselective Synthesis. Natural Products from Chiral Terpenes. Wiley, New York, (1992).
4. Mass spectrometry in structural and stereochemical problems. XLVI11For paper XLV see Beugelmans, R., Williams, D.H., Budzikiewicz, H., and Djerassi, C., J. AM. CHEM. SOC., submitted for publication. the mass spectrometric fragmentation of steroidal ethylene ketals and ethylene thioketals
5. and Bull. Soc. Chim. Fr. 1880 (1964).