He has contributed many learned articles on late medieval Welsh poetry, including the work of Dafydd ap Gwilym, although his main interest was the life and work of poet Gruffudd Hiraethog (d. 1564).
Mynydd Hiraethog | Hiraethog Rural District | Gruffudd Hiraethog | Gruffudd Fychan II | Gruffudd ap Cynan | Gruffudd ab Owain Glyndŵr |