1. Chem. Eng. News, 45, No. 5, 10 (1967).
2. Tomita, M., Ueda, S., and Narisada, M., Yakugaku Zasshi, 79, 186 (1959); Chem. Abstr., 53, 1315d (1959).
3. Verrett, M. J., Marliac, J., and McLaughlin, J., J. Assoc. Offic. Agr. Chemists, 47, 1003 (1964).
4. Neal, P., J. Assoc. Offic. Anal. Chemists, 50, 1338 (1967).
5. Official Methods of Analysis, 10th ed., sees. 26.087–26.091. (Association of Official Agricultural Chemists, Washington, D.C., 1965).