Columbia subject headings:
Industrial hygiene--Law and legislation--United States.
Medical screening--Law and legislation--United States.
Working class--Medical examinations--United States.
Harvard subject headings:
Industrial hygiene--Law and legislation--United States
Medical screening--Law and legislation--United States.
Working class--Medical examinations--United States.
Princeton subject headings:
Industrial hygiene--Law and legislation--United States.
Medical screening--Law and legislation--United States.
Working class--United States--Medical examinations.