1. Annual Book of ASTM Standards, Part 31, “Water,” Standard D1254, p. 366 (1976).
2. Standard Methods for the Examination of Water and Wastewater, 17th Edition, pp. 4-91, Method 4500-N03 F (1992).
3. Chemical Analyses for Water Quality Manual, Department of the Interior, FWPCA, R.A. Taft Engineering Center Training Program, Cincinnati, Ohio 45226 (January, 1966).