Arg. Saesneg gwreiddiol = Original English ed.: John Murray (Publishers) Ltd, 1993.
Deall gwyddoniaeth : deunydd atodol ar gyfer anghenion arbennig by Davies, Carolanne. ISBN 1860851096. Published by Uned Iaith Genedlaethol Cymru CBAC in 1996. Publication and catalogue information, links to buy online and reader comments.