References
- U.S.E.P.A . March 1983 . “Methods for Chemical Analysis of Water and Wastes” , March , Cincinnati, Ohio, , U.S.A. : Environmental Monitoring arid Support Laboratory .
- 1985 . “Standard Methods for Examination for Water and Wastewater”;, , 16th. edition , Washington D.C. : American Public Health Association .
- Kanatharana , P. and Innala , W. 1984 . “The Optimum Conditions of Nitrite Determination” , Hat Yai : Chemistry Department, Prince of Songkla University . unpublished report