Columbia subject headings:
Dortmund (Germany)--Economic conditions.
Labor--Germany--Dortmund--History.
Socialism--Germany--Dortmund--History.
Harvard subject headings:
Dortmund (Germany)--Economic conditions.
Dortmund (Germany)--History.
Labor--Germany--Dortmund--History.
Socialism--Germany--Dortmund--History.
Working class--Germany--Dortmund--Societies, etc.
Princeton subject headings:
Dortmund (Germany)--Economic conditions.
Labor--Germany--Dortmund--History.
Socialism--Germany--Dortmund--History.