Ar y clawr = On cover: PrIME; NCC.
Arg. Saesneg gwreiddiol = Original English ed: Hemel Hempstead, Simon & Schuster, 1990.
Plant, mathemateg a dysgu. ISBN 1871913659. Published by Canolfan Astudiaethau Iaith in 1992. Publication and catalogue information, links to buy online and reader comments.