Columbia subject headings:
Bochum (Germany)--Social conditions.
Social mobility--Germany--Bochum--History.
Working class--Germany--Bochum--History.
Harvard subject headings:
Bochum (Germany)--Social conditions.
Social mobility--Germany--Bochum--History.
Working class--Germany--Bochum--History.
Princeton subject headings:
Bochum (Germany)--Social conditions.
Social mobility--Germany--Bochum--History.
Working class--Germany--Bochum--History.