Birding in Glamorgan is a site guide for the area which was published by the Glamorgan Bird Club in 2009. The editors were Alan S. Rosney and Richard G. Smith, both Club members. The various guides to sites were written by a number of volunteers familiar with the various locations in the County. Most if not all the maps were drawn by Alan Rosney.
This book is now out of print but the text is downloadable for free in pdf format by clicking the image of the front cover on this page. Be aware that the pdf is 199 pages and the file is thus pretty large at 61MB. Be aware also that being published in 2009, some of the site info may be out of date, but most of it is still valid.
It is hoped at some point in the future to produce an online up to date version.