Bibliography Llyfryddiaeth 1 Abbreviations (Byrfoddau) The following abbreviations are used throughout the publication (Defnyddir y byrfoddau canlynol trwy gydol y gyhoeddiad): AB Aberystwyth, National Library of Wales (Aberystwyth, Llyfrgell Genedlaethol Cymru) CDp Cardiff, Central Library (Caerdydd, Llyfrgell Ganolog) Lbl London, British Library (Llundain, Y Llyfrgell Brydeinig) Ob Oxford, Bodleian Library (Rhydychen, Llyfrgell Bodley) Ojec Jesus College, Oxford (Coleg yr Iesu, Rhydychen) 2 Facsimiles of the Robert ap Huw manuscript (Ffacsimilîau o lawysgrif Robert ap Huw) Musica neu Beroriaeth: B. M. Additional MS 14905, with preface by Henry Lewis (Cardiff, 1936). Musica: Llawysgrif Robert ap HuwlMusica: the Robert ap Huw Manuscript, with preface by Wyn Thomas (Godstone, 1982). 3 Books and articles (Llyfrau ac erthyglau) Barddas; or a collection of original documents, illustrative of the theology, wisdom and usages of the Bardo-Druidic system of the Isle of Britain, trans. John Williams ab Ithel, 2 vols. (Llandovery, 1862). Bowen, D. J., 'Graddedigion Eisteddfod Caerwys', Llên Cymru, 2, no. 2 (1952), 129-34. 'Ail Eisteddfod Caerwys a chais 1594', Llên Cymru, 3 (1954-5), 139-61. 'Taleithiau Gwyr wrth Gerdd', Llên Cymru, 17 (1992), 139-42.