Columbia subject headings:
Balkan Peninsula--Foreign relations--Europe--History.
Balkan Peninsula--History--Sources.
Europe--Foreign relations--Balkan Peninsula--History.
Harvard subject headings:
Balkan Peninsula--Foreign relations--Soviet Union.
Balkan Peninsula--Foreign relations.
Balkan Peninsula--History--19th century.
Balkan Peninsula--History--20th century.
Soviet Union--Foreign relations--Balkan Peninsula.
Princeton subject headings:
Balkan Peninsula--Foreign relations--Russia.
Balkan Peninsula--Foreign relations.
Balkan Peninsula--History--19th century.
Balkan Peninsula--History--20th century.
Russia--Foreign relations--Balkan Peninsula.