Adomnán/Adamnán/Eunan/(Naomh Adhamhnán), Ninth Abbot of Iona. Life of Saint Columba. Seventh Century AD:

Halsall, Paul, ed. ‘Medieval Sourcebook: Adamnan: Life of Saint Columba’ at Internet History Sourcebooks Project, March 1998.
https://sourcebooks.fordham.edu/basis/columba-e.asp

Reeves, William, ed. Life of Saint Columba, Founder of H. Y. Written by Adamnan. Edinburgh: Edmonston and Douglas, 1874.
https://ia600900.us.archive.org/11/items/lifeofsaintcolum00adamuoft/lifeofsaintcolum00adamuoft.pdf

Huyshe, Wentworth, tr. The Life of Saint Columba (Columb-Kille) AD 521-597:
Founder of the Monastery of Iona and First Christian Missionary to the Pagan Tribes of North Britain
by Saint Adamnan AD 679-704, Ninth Abbot of the Monastery of Iona.
London: George Routledge & Sons, 1905.
   https://ia801604.us.archive.org/13/items/lifeofsaintcolum00adam/lifeofsaintcolum00adam.pdf
   https://cristoraul.org/ENGLISH/readinghall/pdf-library/Biographies/521-597-Saint-Columba.pdf

Halsall, Paul, ed. ‘Medieval Sourcebook: Adamnan: Life of St. Columba, [Latin Text: Book I and Book II, cc 1-30]’ at Internet History Sourcebooks Project, March 1998.
https://sourcebooks.fordham.edu/basis/columba-l.asp