1. Abel, A. L.: The substituted urea herbicides. Chem. Ind., 1106 (1957).
2. Albert, A., and E. P. Serjeant: Ionization constants of acids and bases. London: Methuen, New York: Wiley 1962.
3. AmChem Products, Inc. (unpublished).
4. American Cyanamid Company (trade booklet).
5. Behrens, R., and H. L. Morton: Some factors influencing activity of 12 phenoxy acids on mesquite root inhibition. Plant Physiol. 38, 165 (1963).