Columbia subject headings:
Foreign workers--United States--History--19th century.
Migration, Internal--Europe--History--19th century.
Working class--Europe--History--19th century.
Working class--United States--History--19th century.
Harvard subject headings:
Foreign workers--United States--History--19th century.
Migration, Internal--Europe--History--19th century.
Working class--Europe--History--19th century.
Working class--United States--History--19th century
Princeton subject headings:
Foreign workers--United States--History--19th century.
Migration, Internal--Europe--History--19th century.
Working class--Europe--History--19th century.
Working class--United States--History--19th century.