Columbia subject headings:
Harvard subject headings:
Environmentalism--History--20th century.
Environmentalism--History--21st century.
Environmentalism--Italy--History--20th century.
Environmentalism--Italy--History--21st century.
Princeton subject headings:
Environmentalism--History--20th century.
Environmentalism--History--21st century.
Environmentalism--Italy--History--20th century.
Environmentalism--Italy--History--21st century.