OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
Gwaith Lewys Môn by Lewys Môn. ISBN 0708305539. Published by Gwasg Prifysgol Cymru ar ran Bwrdd Gwybodau Celtaidd Prifysgol Cymru in 1975. Publication and catalogue information, links to buy online and reader comments.
