Columbia subject headings:
Environmental protection--West (U.S.)
Natural resources--West (U.S.)
West (U.S.)--Description and travel.
Harvard subject headings:
Environmental protection--West (U.S.)
Natural resources--West (U.S.)
West (U.S.)--Description and travel.
Princeton subject headings:
Environmental protection--West (U.S.)
Natural resources--West (U.S.).
West (U.S.)--Description and travel.