Columbia subject headings:
Bulgaria--Foreign relations--United States.
United States--Foreign relations--Bulgaria.
World War, 1914-1918--Diplomatic history.
World War, 1914-1918--Peace.
Harvard subject headings:
Bulgaria--Foreign relations--United States.
Bulgaria--History--Ferdinand I, 1887-1918.
United States--Foreign relations--Bulgaria.
United States--History--1913-1921.
World War, 1914-1918--Diplomatic history
World War, 1914-1918--Peace
Princeton subject headings:
Bulgaria--Foreign relations--United States.
United States--Foreign relations--Bulgaria.
World War, 1914-1918--Diplomatic history.
World War, 1914-1918--Peace.