Columbia subject headings:
Catholic Church--Doctrines--Catholic authors.
Christian union--Catholic Church.
Christian union.
Ecumenical movement--History--Sources.
Luther, Martin, 1483-1546.
Harvard subject headings:
Austria--Church history--20th century--Sources.
Austria--Church history--20th century.
Catholic Church--Austria--History--20th century--Sources.
Catholic Church--Relations--Sources.
Christian union--Catholic Church--History--20th century--Sources.
Ecumenical movement--Austria.
Ecumenical movement.
Luther, Martin, 1483-1546
Pro Oriente.
Stiftung Pro Oriente--History--Sources.
Princeton subject headings: