Columbia subject headings:
Labor unions.
Labor--Great Britain.
Labor--United States.
Harvard subject headings:
Labor movement--Great Britain
Labor movement--United States.
Labor unions.
Working class--Great Britain
Working class--United States
Working class--United States--History--20th century
Princeton subject headings:
Labor movement--Great Britain.
Labor movement--United States.
Labor unions.
Working class--Great Britain.
Working class--United States--History--20th century.