1. American Oil Chemists’ Society, Official and Tentative Methods. Second ed. Edited by V. C. Mehlenbacher, Chicago, 1946. Method Aa 4-38.
2. Association of Official Agricultural Chemists, Official and Tentative Methods of Analysis. Sixth ed. The Society, Washington, 1945. Method 20.47.
3. Brown, C. A., Jr., J. Am. Chem. Soc.,25, 948 (1903).
4. Cruz, A. O., and West, A. P., Philippine J. of Science,47, 487 (1932).
5. Hoffpauir, C. L., J. Assoc. Off. Agri. Chem.,32, 291 (1949).