Columbia subject headings:
Foreign workers, Turkish--Germany (West)--Congresses.
Foreign workers, Turkish--Germany--Ruhr (Region)--Congresses.
Germany (West)--Emigration and immigration--Congresses.
Return migration--Turkey--Congresses.
Ruhr (Germany : Region)--Emigration and immigration--Congresses.
Harvard subject headings:
Foreign workers, Turkish--Germany (West)--Congresses.
Foreign workers, Turkish--Germany--Ruhr (Region)--Congresses.
Immigrants--Germany (West)--Congresses.
Return migration--Turkey--Congresses.
Ruhr (Germany : Region)--Foreign population--Congresses.
Princeton subject headings:
Foreign workers, Turkish--Germany (West)--Congresses.
Foreign workers, Turkish--Germany (West)--Ruhr (Region)--Congresses.
Immigrants--Germany (West)--Congresses.
Immigrants--Germany--Ruhr (Region)--Congresses.
Return migration--Turkey--Congresses.