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 .
x, 306 p. cm. , At head of title: Global Environment Monitoring System. 0631173145

World Environment Day 5 June 2001.

[S.l.] United Nations Environment Programme 2001 .
1 fold-out poster "World Environment Day, 5 June 2001".

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Global freshwater quality a first assessment

World Environment Day 5 June 2001.