"id","author_first1","author_last1","title","year","publication","volume","issue","pages","keyword0","keyword1","type" "1679","Hans","Steffen","Arbeitsmigration aus der Arabischen Rpublik Jemen in die Erdölstaaten der Arabischen Halbinsel","1981","Geographica Helvetica","36","2","73-82","Investment","Migration","journal"