Columbia subject headings:
Hours of labor--Law and legislation--United States--History.
Overtime--Law and legislation--United States--History.
United States. Fair Labor Standards Act of 1938.
Harvard subject headings:
Hours of labor--Law and legislation--United States--History.
Overtime--Law and legislation--United States--History--20th century.
United States. Fair Labor Standards Act of 1938.
Princeton subject headings:
Hours of labor--Law and legislation--United States--History.