Columbia subject headings:
Heidelberg (Germany)--History.
Labor movement--Germany--Heidelberg--History--19th century.
Labor unions--Germany--Heidelberg--History--19th century--Sources.
Labor unions--Germany--Heidelberg--History--19th century.
Harvard subject headings:
Heidelberger Arbeiterverein--History.
Labor movement--Germany--Heidelberg--History--19th century.
Working-men's clubs--Germany--Heidelberg--History--19th century.
Princeton subject headings:
Heidelberger Arbeiterverein--History.
Labor movement--Germany--Heidelberg--History--19th century.
Working-men's clubs--Germany--Heidelberg--History--19th century.