APA (7th ed.) Citation

Adomnán de Iona, S., & Sharpe, R. (1995). Life of St. Columba. Penguin Books.

Chicago Style (17th ed.) Citation

Adomnán de Iona, Santo, and Richard Sharpe. Life of St. Columba. London [etc.]: Penguin Books, 1995.

MLA (9th ed.) Citation

Adomnán de Iona, Santo, and Richard Sharpe. Life of St. Columba. Penguin Books, 1995.