Columbia subject headings:
Bulgaria--Foreign relations--1878-1944.
World War, 1939-1945--Bulgaria.
World War, 1939-1945--Diplomatic history.
World War, 1939-1945--Peace.
Harvard subject headings:
Bulgaria--Foreign relations--1878-1944.
World War, 1939-1945--Bulgaria.
World War, 1939-1945--Diplomatic history.
World War, 1939-1945--Peace.
Princeton subject headings: