Columbia subject headings:
Socialism--Germany--Congresses.
Sozialistische Arbeiterpartei Deutschlands (1875-1890)--Congresses.
Harvard subject headings:
Socialism--Germany--19th century--Sources.
Socialism--Germany--History--19th century--Sources.
Sozialistische Arbeiterpartei Deutschlands (1875-1890)--Congresses.
Working class--Germany--Political activity--History--19th century--Sources.
Working class--Political activity--Germany--History--19th century--Sources.
Princeton subject headings:
Socialism--Germany--Congresses.