1. Primary sources
2. Adam Bremensis. Gesta Hammaburgensis ecclesiae Pontificum, ed. B. Schmeidler, Hanover: MGH Scriptores rerum Germanicarum, 1917. Trans. by F. J. Tschan as Adam of Bremen: History of the Archbishops of Hamburg-Bremen. New York: Columbia University Press, 1959.
3. Annales Quedlinburgenses ed. M. Giese, Hanover: Hahnsche Buchhandlung, 2004.
4. Constantine Porphyrogenitus. De Administrando Imperio, ed. G. Moravscik, trans. R.J. H. Jenkins. Washington: Dumbarton Oaks, 1967.