Columbia subject headings:
Harvard subject headings:
Citizenship--Europe
Citizenship--North America.
Europe--Emigration and immigration--Government policy.
North America--Emigration and immigration--Government policy.
Transatlantic Council on Migration.
Princeton subject headings:
Citizenship--Europe.
Citizenship--North America.
Europe--Emigration and immigration--Government policy.
North America--Emigration and immigration--Government policy.
Transatlantic Council on Migration.