Columbia subject headings:
Environmental policy--Canada.
Environmental policy--United States.
Environmentalists--Canada.
Environmentalists--United States.
Progressivism (Canadian politics)
Progressivism (United States politics)
Harvard subject headings:
Environmental policy--Canada
Environmental policy--United States
Environmentalists--Canada.
Environmentalists--United States
Progressivism (Canadian politics)
Progressivism (United States politics)
Princeton subject headings:
Environmental policy--Canada.
Environmental policy--United States.
Environmentalists--Canada.
Environmentalists--United States.
Progressivism (Canadian politics)
Progressivism (United States politics)