Columbia subject headings:
Europe--Defenses--Sources.
Europe--Foreign relations--Sources.
European federation--Sources.
Security, International--Sources.
Harvard subject headings:
Europe--Defenses--Sources.
Europe--Foreign relations--Sources.
European federation--Sources.
Security, International--Sources.
Princeton subject headings:
Europe--Defenses--Sources.
Europe--Foreign relations--Sources.
European federation--Sources.
Security, International--Sources.