Columbia subject headings:
Balkan Peninsula--Foreign relations--19th century--Sources.
Balkan Peninsula--Foreign relations--20th century--Sources.
Balkan Peninsula--Foreign relations--Treaties.
Harvard subject headings:
Balkan Peninsula--Foreign relations--Treaties.
Balkan Peninsula--Politics and government--19th century--Sources.
Balkan Peninsula--Politics and government--20th century--Sources.
Princeton subject headings: