Columbia subject headings:
Harvard subject headings:
Job descriptions--Research.
Occupational training--Research.
Occupations--History--Research.
Occupations--Research.
Vocational education--Research.
Vocational guidance--Research.
Princeton subject headings:
Job descriptions--Research.
Occupational training--Research.
Occupations--History--Research.
Occupations--Research.
Vocational education--Research.
Vocational guidance--Research.