1. WHO. World Health Report: Bridging the Gaps. Geneva:World Health Organization 1995.
2. The magnitude of the global problem of diarrheal disease: a 10 year update;Bern C;Bull WHO,1992
3. Bartone C. Urban sanitation sewerage and wastewater management: responding to growing household and community demand. In: Proceedings of the Environmentally Sustainable Development Conference. Washington DC:World Bank 1994;136-144.
4. The value of water supply and sanitation in development: an assessment.
5. INEGI. Información Estadística y Geográfica Municipal Vol 6. México City:Instituto Nacional de Geografía e Informática 2000.