APA

Meybeck M., Helmer R., Chapman D. V., Global Environmental Monitoring System, United Nations Environment Programme & World Health Organization. (1990). Global freshwater quality: a first assessment. Cambridge, Mass., U.S.A: Published on behalf of the World Health Organization and the United Nations Environment Programme by Blackwell Reference.

Chicago

Meybeck M, Helmer Richard, Chapman Deborah V, Global Environmental Monitoring System, United Nations Environment Programme and World Health Organization. 1990. Global freshwater quality: a first assessment. Cambridge, Mass., U.S.A: Published on behalf of the World Health Organization and the United Nations Environment Programme by Blackwell Reference.

Harvard

Meybeck M., Helmer R., Chapman D. V., Global Environmental Monitoring System, United Nations Environment Programme and World Health Organization. (1990). Global freshwater quality: a first assessment. Cambridge, Mass., U.S.A: Published on behalf of the World Health Organization and the United Nations Environment Programme by Blackwell Reference.

MLA

Meybeck M, Helmer Richard, Chapman Deborah V, Global Environmental Monitoring System, United Nations Environment Programme and World Health Organization. Global freshwater quality: a first assessment. Cambridge, Mass., U.S.A: Published on behalf of the World Health Organization and the United Nations Environment Programme by Blackwell Reference. 1990.