Columbia subject headings:
Physicians--Licenses--United States--Statistics--Periodicals.
Physicians--United States--Statistics--Periodicals.
Harvard subject headings:
Periodicals.
Physicians--Licenses--United States--Statistics--Periodicals.
Physicians--United States--Statistics--Periodicals.
Princeton subject headings:
Physicians--Licenses--United States--Statistics--Periodicals.
Physicians--United States--Statistics--Periodicals.