Ar drywydd hanes cymdeithasol yr iaith Gymraeg = Towards a social history of the Welsh language : Darlith Goffa Syr Thomas Parry-Williams = Sir Thomas Parry-Williams Memorial Lecture by Ieuan Gwynedd Jones. ISBN 0903878143. Published by Prifysgol Cymru, Aberystwyth in 1994. Publication and catalogue information, links to buy online and reader comments.