Studies: •
Yr Hen Bersoniaid Llengar (1963). Aspects of 18th and 19th century Welsh-language literature. •
R. Williams Parry in the series
Writers of Wales. A study of poet
R. Williams Parry. •
Arthur y Cymry (1975). "The
Arthur of the Welsh". •
Iaith Sir Fôn (1983). The spoken Welsh of
Anglesey. •
Yn Ei Elfen (1992). Etymology. As editor: • ''Blodeugerdd o'r Bedwaredd Ganrif ar Bymtheg'' (1965). Anthology of 19th century Welsh-language verse. •
Rhyddiaith R. Williams Parry (1974).
R. Williams Parry's prose works. •
Gwŷr Môn (1979). "Men of Anglesey", biographies. ==References==