Columbia subject headings:
Catholic Church--Foreign relations--Germany.
Catholic Church--Foreign relations--Italy.
Catholic Church--Relations--Soviet Union.
Church and state--Germany--History--1933-1945.
Church and state--Italy--History--20th century.
Church and state--Soviet Union--20th century.
Communism and Christianity--Catholic Church.
Fascism and the Catholic Church--Italy.
National socialism--Religious aspects.
Pius XI, Pope, 1857-1939.
Harvard subject headings:
Catholic Church--Foreign relations--Germany.
Catholic Church--Foreign relations--Italy.
Catholic Church--Foreign relations--Soviet Union.
Church and state--Germany--History--20th century
Church and state--Italy--History--20th century
Church and state--Soviet Union--History--20th century.
Communism and Christianity--Catholic Church.
Fascism and the Catholic Church--Italy.
Pius XI, Pope, 1857-1939
Princeton subject headings: