Columbia subject headings:
Harvard subject headings:
Catholic Church--Germany--Prussia--History--20th century--Congresses.
Catholic literature--Congresses.
Prussia (Germany)--Church history--20th century--Congresses.
Religion and politics--Germany--Prussia--History--Congresses.
Princeton subject headings:
Catholic Church--Germany--Prussia--History--20th century--Congresses.
Prussia (Germany)--Church history--20th century--Congresses.