Columbia subject headings:
Harvard subject headings:
German letters--History and criticism--Congresses.
Germany--Politics and government--1789-1900--Congresses
Labor movement--Germany--History--19th century--Congresses.
Princeton subject headings:
German letters--History and criticism--Congresses.
Germany--Politics and government--19th century--Congresses.
Labor movement--Germany--History--19th century--Congresses.