Columbia subject headings:
Industrial organization--Case studies.
Workers' travel programs--Case studies.
Working class--Case studies.
Working class--United States--Case studies.
Harvard subject headings:
Industrial organization--Case studies.
Workers' travel programs--Case studies.
Working class--Case studies.
Working class--United States--Case studies.
Princeton subject headings:
Case studies.
Industrial organization--Case studies.
Workers' travel programs--Case studies.
Working class--Case studies.
Working class--United States--Case studies.