Columbia subject headings:
Catholic Church. Pope (1878-1903 : Leo XIII). Rerum novarum.
Christian sociology--Catholic Church.
Church and social problems--Catholic Church.
Labor--Religious aspects--Christianity.
Labor.
Harvard subject headings:
Catholic Church. Pope (1878-1903 : Leo XIII). Rerum novarum.
Christian sociology--Catholic Church.
Christian sociology--Catholic authors.
Church and social problems--Catholic Church
Labor
Labor--Religious aspects--Christianity
Working class
Princeton subject headings:
Catholic Church. Pope (1878-1903 : Leo XIII) Rerum novarum (15 May 1891)
Church and social problems--Catholic Church.
Labor--Religious aspects--Christianity.