Columbia subject headings:
Harvard subject headings:
Balkan Peninsula--Foreign relations--Soviet Union--Sources.
Balkan Peninsula--Politics and government--20th century--Sources.
Communist International--History--Sources.
Nationalism and communism--Balkan Peninsula--History--Sources.
Soviet Union--Foreign relations--Balkan Peninsula--Sources.
Princeton subject headings:
Balkan Peninsula--Foreign relations--Soviet Union--Sources.
Communist International--History--Sources.
Nationalism and communism--Balkan Peninsula--History--Sources.
Soviet Union--Foreign relations--Balkan Peninsula--Sources.