Columbia subject headings:
Industrial relations--Europe--History--20th century.
Labor unions--Europe--History--20th century.
Socialist parties--Europe--History--20th century.
Harvard subject headings:
Industrial relations--Europe--History--20th century.
Labor unions--Europe--History--20th century.
Socialist parties--Europe--History--20th century.
Princeton subject headings:
Industrial relations--Europe--History--20th century.
Labor unions--Europe--History--20th century.
Socialist parties--Europe--History--20th century.