1. Life of St Columba;Adomnán of Iona
2. Atoning for Killing: The Practice of Penance and the Perception of Bloodshed Among the Early Medieval Irish, Fifth to Ninth Century;Burke, David
3. Bieler, Ludwig. The Irish Penitentials. With an Appendix by Daniel A. Binchy, Scriptores Latini Hiberniae (Dublin: Dublin Inst. for Advanced Studies, 1963).
4. The Patrician Texts in the Book of Armagh;Bieler, Ludwig
5. The Career of Columbanus;Bullough, Donald