1. Barthel, W. F., Advances in Pest Control Research, 4, 33 (Interscience Publishers Ltd., London, 1961).
2. For leading references on the chemistry and insecticidal activity of the pyrethrins and related compounds, see Crombie, L., and Elliott, M., Fortschr. Chem. Org. Naturstoffe, 19, 120 (1961).
3. Elliott, M., J. Sci. Food Agric., 5, 505 (1954).
4. Sawicki, R. M., and Thain, E. M., J. Sci. Food Agric., 12, 137 (1961).
5. Sawicki, R. M., Elliott, M., Gower, J. C., Snarey, M., and Thain, E. M., J. Sci. Food Agric., 13, 172 (1962).