Columbia subject headings:
Hours of labor--United States--Statistics--Periodicals.
Labor supply--United States--Statistics--Periodicals.
Wages--United States--Statistics--Periodicals.
Harvard subject headings:
Hours of labor--United States--Statistics--Periodicals.
Labor supply--United States--Statistics--Periodicals.
Wages--United States--Statistics--Periodicals.
Princeton subject headings:
Hours of labor--United States--Statistics--Periodicals.
Labor supply--United States--Statistics--Periodicals.
Periodicals.
Statistics.
Wages--United States--Statistics--Periodicals.