Arg. Saesneg gwreiddiol = Original English ed. : London : Orion Publishing, 1999.
Addasiad Cymraeg gan = Welsh adaptation by : Siân Lewis.
Henri Helynt a'r ysbryd by Francesca Simon. ISBN 9781845211608. Published by Y Ganolfan Astudiaethau Addysg in 2007. Publication and catalogue information, links to buy online and reader comments.