Columbia subject headings:
Agricultural laborers, Foreign--Germany.
Foreign workers, Polish--Germany.
Germany--Emigration and immigration.
Poland--Emigration and immigration.
Harvard subject headings:
Foreign workers, Polish--Germany--Economic conditions.
Foreign workers, Polish--Germany--History--20th century.
Foreign workers, Polish--Social networks--Germany--History--20th century.
Germany--Emigration and immigration.
Seasonal labor--Germany--History--20th century.
Princeton subject headings:
Agricultural laborers, Foreign--Germany.
Foreign workers, Polish--Germany.
Germany--Emigration and immigration.
Poland--Emigration and immigration.