1. Karlson, P., and Lüscher, M., Naturwiss, 46, 63 (1959). Karlson, P., and Butenandt, A., “Ann. Review Entormol.”, 4, 39 (1959).
2. Meystre, Ch., Frey, H., Neher, R., Wettstein A., and Miescher, K., Helv. Chim. Acta, 29, 627 (1946).
3. Gorbach, G., Mikrochimic. Acta, 31, 320 (1944); glacial acetic acid was chosen in place of CCl4 as solvent for the bromination
4. Bellamy, L. J., “The Infra-red Spectra of Complex Molecules”, p. 44 (London, 1954); see also: Burford, R. R., Hewgil, F. R., and Jefferies, P. R., J. Chem. Soc., 2937 (1957). Sondheimer, F., and Mechoulam, R., J. Amer. Chem. Soc., 79, 5029 (1957). Willhelm, B., Steiner, U., and Schinz, H., Helv. Chim. Acta, 41, 1359 (1958).
5. Idler, D. R., and Fagerlund, U. H. M., J. Amer. Chem. Soc., 79, 1988 (1957). Bergmann, W., and Dusza, J. P., Liebigs Ann., 603, 36 (1957).