Columbia subject headings:
Harvard subject headings:
Biographies
Germany--History--Otto IV, 1208-1214.
Germany--Kings and rulers--Biography.
Holy Roman Empire--Kings and rulers--Biography.
Otto IV, Holy Roman Emperor, approximately 1175-1218.
Princeton subject headings:
Germany--History--Otto IV, 1208-1214.
Germany--Kings and rulers--Biography.
Otto IV, Holy Roman Emperor, approximately 1175-1218.