Coelbren y Beirdd
The alphabet system consisted of twenty letters and twenty other representations of elongated vowels that resembled Ancient Greek and could be carved on four-sided pieces of wood and fitted into a frame he called a "peithynen". Williams presented wooden druidic alphabets to friends and notables, and succeeded in persuading many of its authenticity.
Taliesin Williams's book was written about other Coelbrennau'r Beirdd, which is the name of a Welsh language manuscript in the Iolo Manuscripts and two manuscripts in Barddas, one with the subtitle "yn dorredig a chyllell". Iolo Morganwg suggested they were originally the work of bards from Glamorgan who had their manuscripts copied into collections stored at Plas y Fan, Neath Abbey, Margam Abbey and Raglan Library, and compiled by Meurig Dafydd and Lewys Morgannwg, amongst others, in the 1700s. These were suggested to have again been transcribed by Edward Dafydd, John Bradford and Llywelyn Siôn. Moganwg suggested that he had collected some of Siôn and Bradford's manuscripts, while the majority, including all of Lewys Morgannwg's sources, were lost. This claim to authenticity has been questioned by numerous scholars such as Glyn Cothi Lewis.
- "Coelbren y Beirdd – The Bardic Alphabet". National Museum of Wales.
- Cathryn, A Charnell-White (2007). Bardic Circles: National, Regional and Personal Identity in the Bardic Vision of Iolo Morganwg. University of Wales Press. p. 106. ISBN 978-0708320679.
- Jane Williams (18 November 2010). A History of Wales: Derived from Authentic Sources. Cambridge University Press. pp. 6–. ISBN 978-1-108-02085-5. Retrieved 24 October 2012.
- Williams, Taliesin., (ab Iolo), Coelbren Y Beirdd; a Welsh Essay on the Bardic Alphabet, W. Rees, Llandovery, 1840.
- Rob Williams (1852). A biographical dictionary of eminent Welshmen., from the earliest times to the present. W. Rees. pp. 536–. Retrieved 24 October 2012.
- Cambrian Archaeological Association (1846). Archaeologia cambrensis. W. Pickering. pp. 472–. Retrieved 8 November 2012.
- Lewis (Glyn Cothi) (1837). Gwaith Lewis Glyn Cothi: The Poetical Works of Lewis Glyn Cothi, a Celebrated Bard, who Flourished in the Reigns of Henry VI, Edward IV, Richard III, and Henry VII. Hughes. pp. 260–. Retrieved 8 November 2012.
- Iolo Morganwg; Owen Jones; Society for the Publication of Ancient Welsh Manuscripts, Abergavenny (1848). Iolo manuscripts: A selection of ancient Welsh manuscripts, in prose and verse, from the collection made by the late Edward Williams, Iolo Morganwg, for the purpose of forming a continuation of the Myfyrian archaiology; and subsequently proposed as materials for a new history of Wales. W. Rees; sold by Longman and co., London. pp. 10–. Retrieved 24 October 2012.
- Marion Löffler (2007). The literary and historical legacy of Iolo Morganwg, 1826–1926. University of Wales Press. ISBN 978-0-7083-2113-3. Retrieved 24 October 2012.