Columbia subject headings:
Harvard subject headings:
Balkan Peninsula--Ethnic relations--Congresses.
Balkan Peninsula--History--18th century--Congresses.
Balkan Peninsula--History--19th century--Congresses.
Princeton subject headings:
Balkan Peninsula--Ethnic relations--Congresses.
Balkan Peninsula--History--18th century--Congresses.
Balkan Peninsula--History--19th century--Congresses.