Columbia subject headings:
Immigrants--Germany--History.
Poland--Emigration and immigration--History.
Polish people--Germany--History.
Return migration--Poland--History.
Harvard subject headings:
Germany--Emigration and immigration--History--20th century.
Immigrants--Germany--History.
Poland--Emigration and immigration--History--20th century.
Poland--Emigration and immigration--History.
Polish people--Germany--History--20th century.
Polish people--Germany--History.
Return migration--Poland--History.
Return migration--Poland.
Princeton subject headings:
Immigrants--Germany--History.
Poland--Emigration and immigration--History.
Polish people--Germany--History.
Return migration--Poland--History.