Columbia subject headings:
Balkan Peninsula--Economic conditions--Congresses.
Balkan Peninsula--Politics and government--1989---Congresses.
Balkan Peninsula--Social conditions--Congresses.
Harvard subject headings:
Balkan Peninsula--Congresses.
Balkan Peninsula--Economic conditions--Congresses.
Balkan Peninsula--Politics and government--1989---Congresses.
Balkan Peninsula--Social conditions--Congresses.
Princeton subject headings:
Balkan Peninsula--Congresses.