1. 1) IRC International Water and Sanitation Centre: World Water Day 1998, http://www.worldwaterday.org/wwday/1998/, (as of 20th May 2006).
2. 2) UNEP, WHO and UNICEF: Children in the new millennium, p. 62, United Nations Environmental Programme, 2002.
3. 3) UNICEF, Water, Environment and Sanitation: http://www.unicef.org/ethiopia/reallives_389.html, http://www.unicef.org/india/wes_1496.htm, (as of 20th May 2006).
4. 4) WHO: Guidelines for drinking-water quality, 3rd edition, pp. 375-377, World Health Organization, Geneva, 2004.
5. 5) IOM: Dietary reference intake for calcium, phosphorus, Magnesium, Vitamin D, and Fluoride, Institute of Medicine of the National Academies, 1997.