Columbia subject headings:
Communication--United States--Statistics.
Education--United States--Statistics.
Information services--United States--Statistics.
Learning and scholarship--United States--Statistics.
Harvard subject headings:
Communication--United States--Statistics.
Education--United States--Statistics
Information services--United States--Statistics.
Learning and scholarship--United States--Statistics.
Princeton subject headings:
Communication--United States--Statistics.
Education--United States--Statistics.
Information services--United States--Statistics.
Learning and scholarship--United States--Statistics.
Statistics.