Arg Saesneg gwreiddiol = Originally published: London: Hutchinson, 1977.
Cadw gwartheg biff : canllawiau ymarferol ar gyfer ffermwyr a myfyrwyr by Derek H. Goodwin. ISBN 1871913381. Published by Canolfan Astudiaethau Iaith in 1991. Publication and catalogue information, links to buy online and reader comments.