Columbia subject headings:
Harvard subject headings:
Foreign workers--United States--Economic conditions.
Foreign workers--United States--Social conditions.
United States--Emigration and immigration--Economic aspects.
United States--Emigration and immigration--History.
Princeton subject headings:
Foreign workers--United States--Economic conditions.
Foreign workers--United States--Social conditions.
United States--Emigration and immigration--Economic aspects.
United States--History--Emigration and immigration.