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Helmer, Richard ,  World Health Organization. Prevention of Environmental Pollution Unit ,  International Drinking Water Supply and Sanitation Decade ,  Inter-Regional Meeting on Rural Water Supply and Sanitation (1984 : Umea, Sweden) ,  [Water quality, health and the Decade : reflections on a new programme approach / Richard Helmer]

Lloyd, Barry ,  Helmer, Richard ,  World Health Organization ,  United Nations Environment Programme ,  [Surveillance of drinking water quality in rural areas / Barry Lloyd, Richard Helmer]

Lloyd, Barry ,  Helmer, Richard ,  World Health Organization ,  United Nations Environment Programme ,  [Surveillance of drinking water quality in rural areas / Barry Lloyd, Richard Helmer]

Helmer, Richard ,  World Health Organization. Prevention of Environmental Pollution Unit ,  International Drinking Water Supply and Sanitation Decade ,  Inter-Regional Meeting on Rural Water Supply and Sanitation (1984 : Umea, Sweden) ,  [Water quality, health and the Decade : reflections on a new programme approach / Richard Helmer]