Arg. Saesneg gwreiddiol = Original English ed.: Cambridge: Cambridge University Press, 1997.
Addasiad Cymraeg gan = Welsh adaptation by: Glenys M. Roberts.
SMP 11-16. Llyfr A6. ISBN 1860851444. Published by Uned Iaith Genedlaethol Cymru in 1997. Publication and catalogue information, links to buy online and reader comments.