Gwaith gronw gyriog, iorwerth ab y cyriog, mab clochyddyn, gruffudd ap Tudor goch ac ithel ddu /
Ifans, Rhiannon.
University of Wales Centre for Advanced Welsh and Celtic Studies.
Aberystwyth : Canolfan Uwechfrydiau Cymreig a Cheltaidd, Prifysgol Cymru,
1997.