Columbia subject headings:
Harvard subject headings:
Catholic Church. Pope (1922-1939 : Pius XI). Quadragesimo anno.
Church and social problems--Catholic Church
Labor--Religious aspects--Christianity
Princeton subject headings:
Catholic Church. Pope (1922-1939 : Pius XI). Quadragesimo anno (15 May 1931)
Church and social problems--Catholic Church.
Labor--Religious aspects--Christianity.