Columbia subject headings:
Socialism--Germany--History--19th century--Sources.
Socialism--History--19th century--Sources.
Harvard subject headings:
Socialism--Germany--19th century--Sources.
Socialism--Germany--History--19th century--Sources.
Socialism--History--19th century--Sources.
Princeton subject headings:
Socialism--Germany--History--19th century--Sources.
Socialism--History--19th century--Sources.