Columbia subject headings:
Harvard subject headings:
European Union countries--Foreign relations--20th century.
European Union countries--Foreign relations--21st century.
European Union--History--20th century.
European Union--History--21st century.
International relations--History--20th century
International relations--History--21st century
Princeton subject headings:
European Union countries--Foreign relations--20th century.
European Union countries--Foreign relations--21st century.
European Union--History--20th century.
European Union--History--21st century.
International relations--History--20th century.
International relations--History--21st century.