Columbia subject headings:
Harvard subject headings:
International Labour Organization--History--Congresses.
International labor activities--History--20th century--Congresses.
Labor policy--History--20th century--Congresses.
Labor unions--History--20th century--Congresses.
Princeton subject headings:
International Labour Organization--History.
International labor activities--History--20th century.
Labor policy--History--20th century.
Labor unions--History--20th century.