Columbia subject headings:
Europe, Eastern--Research--Germany--History--20th century.
Germany--Relations--Poland.
Poland--Relations--Germany.
Harvard subject headings:
Europe, Eastern--Research--Germany--History--20th century.
Germany--Relations--Poland.
Poland--Relations--Germany
Princeton subject headings:
Europe, Eastern--Research--Germany--History--20th century.
Germany--Relations--Poland.
Poland--Relations--Germany.