Columbia subject headings:
Ecology--England--Mersey River Valley--Congresses.
Land use--England--Mersey River Valley--Congresses.
Harvard subject headings:
Ecology--England--Mersey River Watershed--History--Congresses.
Mersey River Watershed (England)--History--Congresses.
Princeton subject headings:
Ecology--England--Mersey River Estuary--Congresses.
Land use--England--Mersey River Estuary--Congresses.