Argraffiad Saesneg gwreiddiol = Original English edition : Oxford : Rigby, 2000.
Addasiad Cymraeg gan = Welsh adaptation by : Awdurdod Cymwysterau, Cwricwlwm ac Asesu Cymru.
Ffocws rhifedd : llyfr ymarfer 5 by L. J. Frobisher. ISBN 0948469870. Published by Wasg Taf Cyf in 2002. Publication and catalogue information, links to buy online and reader comments.