Columbia subject headings:
Austria--Foreign relations--Bulgaria--History--Exhibitions.
Bulgaria--Foreign relations--Austria--History--Exhibitions.
World War, 1914-1918--Diplomatic history--Exhibitions.
Harvard subject headings:
Austria--Foreign relations--Bulgaria--History--Exhibitions.
Bulgaria--Foreign relations--Austria--History--Exhibitions.
World War, 1914-1918--Diplomatic history--Exhibitions.
Princeton subject headings:
Austria--Foreign relations--Bulgaria--History--Exhibitions.
Bulgaria--Foreign relations--Austria--History--Exhibitions.
World War, 1914-1918--Diplomatic history--Exhibitions.