Columbia subject headings:
Germany--Economic conditions--19th century.
Germany--Social conditions.
Proletariat--History.
Working class--Germany--Biography.
Working class--Germany--History--19th century.
Harvard subject headings:
Germany--Economic conditions--19th century.
Germany--Social conditions.
Proletariat--History.
Working class--Germany--Biography.
Working class--Germany--History--19th century
Princeton subject headings:
Germany--Economic conditions--19th century.
Germany--Social conditions.
Proletariat--History.
Working class--Germany--Biography.
Working class--Germany--History--19th century.