Columbia subject headings:
Harvard subject headings:
Germany--Emigration and immigration--Government policy.
Germany--Emigration and immigration--History.
Immigrants--Germany--History.
Poland--Emigration and immigration--History.
Polish people--Germany--History.
Polish people--Germany--Social conditions.
Princeton subject headings:
Germany--Emigration and immigration--Government policy.
Germany--Emigration and immigration--History.
Immigrants--Germany--History.
Immigrants--Poland--History.
Poland--Emigration and immigration--History.