Columbia subject headings:
Harvard subject headings:
Industrial relations--Germany--History--Sources.
Labor movement--Germany--History--Sources.
Labor unions--Germany--History--Sources.
Pamphleteers--Germany--History--Sources.
Pamphlets--Bibliography.
Pamphlets--History--Sources.
Socialism--Germany--History--Sources.
Socialism--Germany--Sources.
Working class--Germany--History--Sources.
Princeton subject headings:
Working class--Germany--Political activity--History.