Columbia subject headings:
Harvard subject headings:
Industrial safety--Canada.
Industrial safety--Mexico.
Industrial safety--United States
Occupational health services--Government policy--Canada.
Occupational health services--Government policy--Mexico.
Occupational health services--Government policy--United States.
Princeton subject headings:
Industrial hygiene--Law and legislation--Canada.
Industrial hygiene--Law and legislation--Mexico.
Industrial hygiene--Law and legislation--United States.
Industrial safety--Law and legislation--Canada.
Industrial safety--Law and legislation--Mexico.
Industrial safety--Law and legislation--United States.