Arg. Saesneg gwreiddiol = Original English ed.: Harlow: Longman Group, 1994.
Addasiad Cymraeg gan = Welsh adaptation by: Greville James.
Gwersylla: dim diolch by Jenny Oldfield. ISBN 1860853293. Published by Uned Iaith Genedlaethol Cymru in 1998. Publication and catalogue information, links to buy online and reader comments.