Argraffiad Saesneg gwreiddiol = Original English edition: Oxford : Oxford University Press, 1987.
Addasiad Cymraeg gan = Welsh adaptation by: Emily Huws.
Teitl o'r clawr = Title from cover.
Twll yn y to by Roderick Hunt. ISBN 0861742583. Published by Gwasg Addysgol Drake in 2000. Publication and catalogue information, links to buy online and reader comments.