Columbia subject headings:
Clerks--United States.
Middle class--United States.
Skilled labor--United States.
Working class--United States.
Harvard subject headings:
Clerks--United States.
Middle class--United States.
Skilled labor--United States.
Working class--United States
Princeton subject headings:
Clerks--United States.
Middle class--United States.
Skilled labor--United States.
Working class--United States.