Lloyd, Barry. creator Helmer, Richard World Health Organization United Nations Environment Programme text Burnt Mill, Harlow, Essex, England New York Longman Scientific & Technical J. Wiley 1991 monographic xvi, 171 p. : ill., maps ; 24 cm. "Published on behalf of the World Health Organization and the United Nations Environment Programme." Water-supply, Rural Water quality Drinking water 628 JWI 1991 A039 Or. 0582063302 047021709X (U.S.)