1. P. De Mayo, The Chemistry of Natural Products, Vols. 2 and 3, ed. K. W. Bentley, Interscience, New York 1959.
2. J. Simonsen, The Terpenes, Vols. 1–5, Cambridge University Press.
3. D. H. R. Barton, in Chemistry of Carbon Compounds, ed. E. H. Rodd, Vol. 2B, Elsevier, London 1953, pp. 489–764.
4. A. Burger, Medicinal Chemistry, 1st edn., Vol. 1, Interscience, New York 1951, p. 286.
5. L. Ruzicka, Proc. chem. Soc. Lond., 341 (1959).