Columbia subject headings:
Catholic Church. Pope (1878-1903 : Leo XIII). Rerum novarum.
Christian sociology--Catholic Church.
Church and social problems--Catholic Church.
Harvard subject headings:
Catholic Church. Pope (1878-1903 : Leo XIII). Rerum novarum--Anniversary, 1991.
Catholic Church. Pope (1878-1903 : Leo XIII). Rerum novarum.
Christian sociology--Catholic Church--History--19th century.
Christian sociology--Catholic Church.
Church and social problems--Catholic Church
Church and social problems--Catholic Church--History--19th century.
Labor--Religious aspects--Christianity--Germany--History--19th century.
Leo XIII, Pope, 1810-1903--Contributions in social teaching.
Princeton subject headings: