Columbia subject headings:
Academic libraries--Canada--Statistics.
Academic libraries--United States--Statistics.
Research libraries--Canada--Statistics.
Research libraries--United States--Statistics.
Harvard subject headings:
Academic libraries--Canada--Statistics.
Academic libraries--Statistics--Canada--Academic libraries--Statistics--Periodicals.
Academic libraries--United States--Statistics--Periodicals.
Academic libraries--United States--Statistics.
Research libraries--Canada--Statistics--Periodicals.
Research libraries--Canada--Statistics.
Research libraries--United States--Statistics--Periodicals.
Research libraries--United States--Statistics.
Princeton subject headings:
Academic libraries--Canada--Statistics--Periodicals.
Academic libraries--United States--Statistics--Periodicals.
Research libraries--Canada--Statistics--Periodicals.
Research libraries--United States--Statistics--Periodicals.