Columbia subject headings:
Labor unions--Officials and employees--Germany--History--Congresses.
Sozialdemokratische Partei Deutschlands--Congresses.
Working class--Political activity--Germany--History--Congresses.
Harvard subject headings:
Labor unions--Germany--Officials and employees--History--Congresses.
Sozialdemokratische Partei Deutschlands--Congresses.
Working class--Germany--History--Congresses.
Working class--Germany--Political activity--History--Congresses.
Princeton subject headings:
Labor unions--Germany--Officials and employees--History--Congresses.
Sozialdemokratische Partei Deutschlands--Congresses.
Working class--Germany--History--Congresses.