Columbia subject headings:
Catholic Church--History--19th century.
Catholic Church--History--20th century.
Church history--19th century.
Church history--20th century.
Harvard subject headings:
Catholic Church--History--19th century.
Catholic Church--History--20th century.
Church history--19th century
Church history--20th century.
Princeton subject headings:
Catholic Church--History--19th century.
Catholic Church--History--20th century.
Church history--19th century.
Church history--20th century.