Arg. Saesneg gwreiddiol = Original English ed.: Oxford: Macmillan Publishers, 1991.
Addasiad Cymraeg gan = Welsh adaptation by: Marian Beech Hughes.
Sŵ Sarg by Paul Shipton. ISBN 1856444074. Published by Y Ganolfan Astudiaethau Addysg in 1999. Publication and catalogue information, links to buy online and reader comments.