Called Donnchad[h] IV by Dauvit Broun, "Anglo-French Acculturation", p. 138; called Duncan (IV) Macduff and ninth earl of Fife by Andrew McDonald, "Macduff family, earls of Fife (per. c.1095–1371)", Oxford Dictionary of National Biography, Oxford University Press, 2004 , accessed 8 Sept 2007; called Duncan (IV) by Bannerman, "Macduff of Fife", p. 33; in Angus, William, editor, 'Miscellaneous Charters 1315-1401' in Miscellany of The Scottish History Society, volume 5, Edinburgh, 1933: 25, where he is given in a latin charter as Duncanus comes de Fyff, and p.63 where he is given as Duncanus comes de Fyff, and where the modern author calls him the tenth Earl of Fife. The number of earls of Fife before Donnchadh IV is not actually known; many older numberings include Ethelred, lay abbot of Dunkeld; this is based on a mistake produced by translation problems from a late 11th-century Gaelic charter; see Bannerman, "Macduff of Fife", p. 30, n. 3. There were at least two, and almost certainly more, earls of Fife before either Ethelred or Causantín; see Bannerman, "Macduff of Fife", passim.
