World Health Organization. (1993). Guidelines for drinking - water quality: Recommendations. World Health Organization.
Dyfyniad Arddull ChicagoWorld Health Organization. Guidelines for Drinking - Water Quality: Recommendations. Geneva: World Health Organization, 1993.
Dyfyniad MLAWorld Health Organization. Guidelines for Drinking - Water Quality: Recommendations. World Health Organization, 1993.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.