Hawliau tramwy cyhoeddus ym Mharc Cenelaethol Eryri : adroddiad ar arolwg LINKS 1992-1996 = Public rights of way in the Snowdonia National Park : report of LINKS survey 1992-1996 by Iwan Huws. ISBN 094816106X. Published by Parc Cenedlaethol Eryri in 1996. Publication and catalogue information, links to buy online and reader comments.