Columbia subject headings:
Latin letters, Medieval and modern--History--To 1500.
Sultans--Turkey--History.
Turkey--Kings and rulers--Correspondence--History and criticism.
Harvard subject headings:
Latin letters, Medieval and modern--History--To 1500.
Sultans--Turkey--History.
Turkey--Kings and rulers--Correspondence--History and criticism.
Princeton subject headings:
Sultans--Turkey--Correspondence.
Sultans--Turkey--History.
Turkey--Foreign relations.
Turkey--History--To 1453.
Turkey--Kings and rulers--Biography.