Argraffiad Saesneg gwreiddiol = Original English edition : London : Orion Children's Books, 1997.
Addasiad Cymraeg gan = Welsh adaptation by : Elin Meek.
Henri helynt a'r llau by Francesca Simon. ISBN 9781845211257. Published by Y Ganolfan Astudiaethau Addysg in 2006. Publication and catalogue information, links to buy online and reader comments.