Columbia subject headings:
Bulgaria--History--Ferdinand I, 1887-1918.
Bulgaria--Kings and rulers--Biography.
Ferdinand I, Czar of Bulgaria, 1861-1948.
Harvard subject headings:
Bulgaria--History--Ferdinand I, 1887-1918.
Bulgaria--Kings and rulers--Biography.
Ferdinand I, Czar of Bulgaria, 1861-1948.
Princeton subject headings:
Bulgaria--History--Ferdinand I, 1887-1918.
Bulgaria--Kings and rulers--Biography.
Ferdinand I, Czar of Bulgaria, 1861-1948.