Columbia subject headings:
Harvard subject headings:
Engineers--United States--Statistics.
Psychologists--Employment--United States--Statistics.
Psychologists--Employment--United States.
Psychologists--United States--Statistics.
Scientists--United States--Statistics.
Princeton subject headings:
Engineers--United States--Statistics.
Psychologists--Employment--United States.
Psychologists--United States--Statistics.
Scientists--United States--Statistics.
Statistics.