Originally published: 1974. Re-issued with a new introduction by Damian Bracken.
OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
Columbanus : in his own words by Tomás Ó Fiaich. ISBN 9781847303578. Published by Veritas in 2012. Publication and catalogue information, links to buy online and reader comments.
