Columbia subject headings:
Harvard subject headings:
Boundaries--Economic aspects--Europe.
Boundaries--Social aspects--Europe.
Boundary disputes.
Europe--Boundaries.
Europe--Foreign relations.
Geopolitics--Europe.
Princeton subject headings:
Boundaries--Economic aspects--Europe.
Boundaries--Social aspects--Europe.
Boundary disputes.
Europe--Boundaries.
Europe--Foreign relations.
Geopolitics--Europe.