Arg. Saesneg gwreiddiol = Original English ed.: Oxford: Heinemann English Language Teaching, 1991.
Addasiad Cymraeg gan = Welsh adaptation by: Marian Beech Hughes.
Bril! by Alan C. McLean. ISBN 185644404X. Published by Y Ganolfan Astudiaethau Addysg in 1999. Publication and catalogue information, links to buy online and reader comments.