Despy, G. (1953). "La carrière lotharingienne du pape Étienne IX," in: Revue belge de philologie et d’histoire, XXXI (1953), pp. 955–972. Kehr, Paulus Fridolinus (1935). Italia pontificia. Vol. VIII: Regnum Normannorum—Campania Berlin: Weidmann. (in Latin) Kelly, J. N. D. and Walsh, M. J. (2010). Oxford Dictionary of Popes. second ed. Oxford: Oxford University Press. pp. 149–150. Mann, Horace Kinder (1913), "Pope Stephen (IX) X." Catholic Encyclopedia, Volume 14 (1913). Retrieved: 16 June 2021. Schmale, F.-J. (1963). "Étienne IX," in: Dictionnaire d’histoire et de géographie ecclésiastiques, Vol. XV, Paris 1963, coll. 1198-1203. [sources] External links Parisse, Michel (2019). "STEFANO IX, papa." Dizionario Biografico degli Italiani Volume 94 (2019). Stephen 09 Stephen 09 Stephen 09 Abbots of Monte Cassino House of Limburg People from Lorraine 1020s births 1058 deaths 11th-century French clergy Stephen 09 11th-century German clergy House of Ardenne–Verdun