1. Day, H. M., and Bradley, M. H., U.S. Patent 2,541,003 (Feb. 6, 1951).
2. Jayne, D. W., Day, M. H., and Nolan, K. G. U.S. Patent 2,468,075 (April 26, 1949).
3. Linser, H., in The Chemistry and Mode of Action of Plant Growth Substances, by Wain, R. L., and Wightman, F., 141 (Butterworth's Scientific Publications, 1956).
4. Takeda, A., J. Org. Chem., 22, 1096 (1957).
5. Godson, D. H., Leafe, E. L., Lush, G. B., and Stevenson, H. A., Patent 862,226 (March 8, 1961).