Columbia subject headings:
Protestants--Germany--History--20th century.
Protestants--Poland--History--20th century.
Theology--Germany--History--20th century.
Theology--Poland--History--20th century.
Harvard subject headings:
Protestantism--Germany--History--20th century.
Protestantism--Poland--History--20th century.
Theology--Germany--History--20th century.
Theology--Poland--History--20th century.
Princeton subject headings: