1. American Public Health Association. 1985. Standard Methods for the Examination of Water and Wastewater. 16th edition. Washington, DC.
2. EPA-600/8-78-;Bordner,1978
3. Microbial indicator systems for assessing water quality
4. 1985. U.S. Environmental Protection Agency's Methods Equivalency Program for Drinking Water Samples. U. S. Environmental Protection Agency, Cincinnati, OH.