Columbia subject headings:
Harvard subject headings:
America--Emigration and immigration--Congresses.
International division of labor--Congresses.
Migrant labor--America--Congresses.
Working class--America--Congresses.
Princeton subject headings:
America--Emigration and immigration--Congresses.
International division of labor--Congresses.
Labor--America--Congresses.
Migrant labor--America--Congresses.