Columbia subject headings:
Bible--Study and teaching--Catholic Church.
Catholic Church--History.
Encyclicals, Papal.
Leo XIII, Pope, 1810-1903.
Pius XII, Pope, 1876-1958.
Harvard subject headings:
Catholic Church--Doctrines--History--Congresses.
Catholic Church--History.
Leo XIII, Pope, 1810-1903
Pius XII, Pope, 1876-1958.
Princeton subject headings: