1. Earth Summit, Comprehensive Assessment of the Freshwater Resources of the World. Agenda 21, Chapter 18, paragraphs 18.6 and 18.8, as endorsed at the United Nations Conference on Environment and Development, Rio de Janeiro, June 1992.
2. United Nations (UN), Comprehensive Assessment of the Freshwater Resources of the World, 1999, http://geocompendium.grid.unep.ch/reference_scheme/final_version/GEO/Geo-2-121.htm (Accessed October 2005).
3. Unesco, Trace Elements in Water and Public Health, http://www.iah.org/briefings/Trace/trace.htm (Accessed October 2004).
4. Appropriate deflouridation technology for use in flourotic areas in Tanzania
5. Arsenic treatment considerations