Columbia subject headings:
Conservation of natural resources--Government policy--United States--History--20th century.
Conservation of natural resources--United States--History--20th century.
Roosevelt, Franklin D. (Franklin Delano), 1882-1945.
Harvard subject headings:
Conservation of natural resources--Government policy--United States--History--20th century.
Conservation of natural resources--United States--History--20th century.
Roosevelt, Franklin D. (Franklin Delano), 1882-1945
Princeton subject headings:
Conservation of natural resources--Government policy--United States--History--20th century.
Conservation of natural resources--United States--History--20th century.
Roosevelt, Franklin D. (Franklin Delano), 1882-1945.