Columbia subject headings:
Harvard subject headings:
Germany--Foreign economic relations--20th century--Congresses.
Germany--Foreign economic relations--Poland--Congresses.
Poland--Foreign economic relations--20th century--Congresses.
Poland--Foreign economic relations--Germany--Congresses.
Princeton subject headings:
Germany--Economic policy--20th century.
Germany--Foreign relations--Poland.
Poland--Economic policy--20th century.
Poland--Foreign relations--Germany.