Columbia subject headings:
United States--Emigration and immigration--Statistics--Periodicals.
Visas--United States--Statistics--Periodicals.
Harvard subject headings:
United States--Emigration and immigration--Statistics--Periodicals.
Visas--United States--Statistics--Periodicals.
Princeton subject headings:
Periodicals.
Statistics.
United States--Emigration and immigration--Statistics--Periodicals.
Visas--United States--Statistics--Periodicals.