"Adnoddau addysgu mathemateg y gellir eu llungopïo" - t.p.
Arg. Saesneg gwreiddiol = Original English ed.: London : A. & C. Black, 2008.
Ffeithiau rhif a chyfrifiadau. Blwyddyn 1 by Hilary Koll. ISBN 9781845213770. Published by CAA in 2010. Publication and catalogue information, links to buy online and reader comments.