Cyhoeddwyd yn wreiddiol = Originally published: Cambridge: Cambridge University Press, 1981.
Y ddrama gyfoes : damcaniaethau ac arferion. Cyfrol 2, Symbolaeth, swrealaeth a'r abswrd by J. L. Styan. ISBN 9781843236887. Published by Gomer in 2007. Publication and catalogue information, links to buy online and reader comments.