Argraffiad Saesneg gwreiddiol = Original English edition : Oxford : Rigby, 1999.
Addasiad Cymraeg gan Awdurdod Cymwysterau, Cwricwlwm ac Asesu Cymru = Welsh adaptation by Qualifications, Curriculum and Assessment Authority for Wales.
Ffocws rhifedd 4 : problem yr wythnos by John Spooner. ISBN 0948469803. Published by Gwasg Taf in 2002. Publication and catalogue information, links to buy online and reader comments.