Columbia subject headings:
Harvard subject headings:
Germany--Politics and government.
Middle class--Germany--Political activity--History.
Middle class--Political activity--Germany--History.
Social classes--Germany--History
Working class--Germany--Political activity--History.
Working class--Political activity--Germany--History.
Princeton subject headings:
Germany--Politics and government.
Middle class--Germany--Political activity--History.
Social classes--Germany--History.
Working class--Germany--Political activity--History.