1. American Society for Testing Materials, ASTM Designation, E 148–59T.
2. Association of Official Agricultural Chemists, “Official Methods of Analysis,” 8th ed., pp. 801–811, Washington, D. C., 1955.
3. Semimicrodetermination of Phosporus in Organic Compounds
4. Application of a semi-quantitative estimation of nitrogen and other elements in organic microanalysis