1. United Nations 2000 United Nations Millennium Declaration
2. Causes of outbreaks associated with drinking water in the United States from 1971 to 2006;Craun;Clin Microbiol Rev,2010
3. US Environmental Protection Agency 2015 http://water.epa.gov/drink/info/well/index.cfm
4. US Environmental Protection Agency 2015 http://water.epa.gov/infrastructure/drinkingwater/pws/index.cfm