Columbia subject headings:
North Atlantic Treaty Organization--Membership.
Security, International.
Harvard subject headings:
Crimea (Ukraine)--Annexation to Russia--Congresses.
Crimea (Ukraine)--History--2014---Congresses.
North Atlantic Treaty Organization--Membership--Congresses.
North Atlantic Treaty Organization--Ukraine--Congresses.
Peace-building--Ukraine--Crimea--Congresses.
Russia (Federation)--Foreign relations--Ukraine--Congresses.
Security, International--Congresses
Ukraine Conflict, 2014---Congresses.
Ukraine--Foreign relations--Russia (Federation)--Congresses.
Princeton subject headings:
North Atlantic Treaty Organization--Membership.
Security, International.