Columbia subject headings:
Harvard subject headings:
Environmental protection--Great Lakes Region (North America)
Environmental protection--Great Lakes Region.
Freshwater ecology--Great Lakes Region (North America)
Freshwater ecology--Great Lakes Region.
Human ecology--Great Lakes Region (North America)
Human ecology--Great Lakes Region.
Water quality--Great Lakes Region (North America)
Water quality--Great Lakes Region.
Princeton subject headings:
Great Lakes (North America)--History.
Lake ecology--Great Lakes.
Water--Pollution--Great Lakes.