Columbia subject headings:
Harvard subject headings:
Endangered species--Law and legislation--United States
Foreign trade regulation--United States.
Hunting trophies--Law and legislation--United States.
Polar bear--Law and legislation--United States.
Princeton subject headings:
Endangered species--Law and legislation--United States.
Foreign trade regulation--United States.
Hunting trophies--Government policy--United States.
Polar bear--Law and legislation--United States.