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Dyfyniad Arddull ChicagoWorld Health Organization and United Nations Environment Programme. Who Guidelines for the Safe Use of Wastewater Excreta and Greywater: Waste Water and Excreta Use in Agriculture. Geneva: World Health Organization, 2006.
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Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.