Great Britain. National Rivers Authority. (1991). The Quality of rivers, canals and estuaries in England and Wales: Report of the 1990 survey. The Authority.
Παραπομπή σε μορφή Chicago (17η εκδ.)Great Britain. National Rivers Authority. The Quality of Rivers, Canals and Estuaries in England and Wales: Report of the 1990 Survey. Bristol: The Authority, 1991.
Παραπομπή σε μορφή MLA (8th εκδ.)Great Britain. National Rivers Authority. The Quality of Rivers, Canals and Estuaries in England and Wales: Report of the 1990 Survey. The Authority, 1991.
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