Mae'r gyfres yn cynnwys gohebiaeth, nodiadau a phapurau amrywiol, [1930 x 1999], yn ymwneud â'r iaith a llenyddiaeth Gymraeg, a grewyd ac a gasglwyd gan yr Athro J. E. Caerwyn Williams.

Cyhoeddiadau a phapurau ymchwil G. J. Williams, [1911x1963], ar lenyddiaeth Gymraeg, gan gynnwys deunydd perthynol i'r cyhoeddiad Gramadegau'r Penceirddiaid; nifer o ddarlithoedd ac erthyglau; ynghyd ag adysgrifau o lawysgrifau o wahanol ffynonellau a nodiadau amrywiol.

Papurau Cymdeithas Lyfrau Ceredigion,1951-1993, yn cynnwys gohebiaeth, adroddiadau, copïau llawysgrif a theipysgrif, proflenni a phapurau eraill yn ymwneud â chyhoeddiadau penodol, 1954-1991; papurau gweinyddol yn cynnwys gohebiaeth, cofnodion ac agendâu, adroddiadau blynyddol a ffigurau gwerthiant, 1951-1993; gohebiaeth gyffredinol gyda sefydliadau eraill, 1951-1993; ffeiliau yn ymwneud â Welsh Teldisc,1951-1992; a chofnodion ariannol, 1954-1991 = Papers of Cymdeithas Lyfrau Ceredigion, 1951-1993, including correspondence, reports, manuscript and typescript copies, proofs and other papers relating to specific publications, 1954-1991; administrative papers including correspondence, minutes and agendas, annual reports and sales figures, 1951-1993; general correspondence with other organisations, 1951-1993; files relating to Welsh Teldisc, 1951-1992; and financial records, 1954-1991.

Papurau ychwanegol yn perthyn i'r gymdeithas, gan gynnwys papurau gweinyddol, cofnodion cyfarfodydd, papurau ariannol, gohebiaeth a phapurau eraill.

Papurau a phregethau y Parch. Euros Bowen,1922-1983, yn cynnwys drafftiau cerddi, nodiadau darlithoedd ar ddiwinyddiaeth ac athroniaeth, 1929-1933; gweithiau llenyddol,1944-1977; dyddiaduron gwyliau, 1955-1980; gohebiaeth yn ymwneud â Chomisiwn Sefydlog Ymgynghorol Litwrgi yr Eglwys yng Nghymru a drafftiau o litwrgïau, 1967-1974; a thorion papur newydd a phapurau printiedig, 1953-1963 = Papers and sermons of the Rev. Euros Bowen, 1922-1983, including drafts of poems, lecture notes on theology and philosophy, 1929-1933; literary works, 1944-1977; holiday diaries, 1955-1980; correspondence realting to the Standing Liturgical Advisory Commission and draft liturgies, 1967-1974; and newspaper cuttings and printed papers, 1953-1983.

Mae papurau Glyn M. Ashton a dderbyniwyd yn 1992 yn cynnwys ei bapurau ymchwil, ynghyd â nifer o ysgrifau ac adolygiadau, gweithiau llenyddol, sgriptiau radio, gohebiaeth a deunydd printiedig. -- Mae'r papurau a dderbyniwyd yn 2001 yn cynnwys nodiadau a drafftiau o'i erthyglau a'i ddarlithoedd; copïau o lawysgrifau; drafftiau o'i nofelau a'i ddramâu; gohebiaeth; ynghyd â chofnodion Pwyllgor Eisteddfod y Barri, 1968.

Torion papur, [1920x1963], yn ymwneud â Iolo Morganwg, llenyddiaeth Gymraeg, crefydd, diwylliant ac addysg yng Nghymru. Yn eu plith ceir un bwndel o dorion, 1954-1956, o ysgrifau 'Cartrefi Cymru' gan Bob Owen, Croesor, yn Y Cymro.

One of two volumes of 'Nefydd' miscellanea, including material relating to Welsh literature and bibliography, eisteddfod adjudications, etc.

One of two volumes of 'Nefydd' miscellanea, including material relating to Welsh literature and bibliography, eisteddfod adjudications, etc.

Miscellaneous notes by Walter Davies relating mainly to Welsh literature, history, and archaeology.

Drafts of articles relating to Welsh literature and history and to Celtic institutions; lists of Welsh words derived from English and of words common to both branches of the Celtic family; and a poem entitled 'Rhiangerdd Gwenfalwy o Gastell Caerphili' by 'Idwal Trefor', 1874.

A Latin vocabulary, notes for the study of the Mabinogion, extracts from printed sources, notes on 'Y Gogynfeirdd' and their vocabulary, etc.

Two volumes of miscellaneous transcripts mainly in the hand of Walter Davies (Gwallter Mechain, 1761-1849), relating to the antiquities, history, topography, language, and literature of Wales. They include catalogues of Welsh manuscripts; transcripts of manuscripts of Evan Evans (Ieuan Brydydd Hir), of letters of Edward Lhuyd, Lewis Morris, Goronwy Owen, etc., of Strata Marcella abbey charters, of monumental inscriptions, of Evan Evans's transcripts of Richard Farrington's archaeological notes, etc.; notes on Llanerfyl, Llangadfan, and Garthbeibio, written by William Jones, Llangadfan, and sent by him, with letters, to Walter Davies; a letter, 1792, from Edward Williams (Iolo Morganwg) to Walter Davies; an extract, by Lewis Morris, from his Celtic Remains; Marwnad Lewis Morys ... by Goronwy Owen, in the autograph of Evan Evans; etc. Both volumes are indexed.

Addresses by Meredith J. Hughes on 'Myth and legend in the literature of Wales', 1914, and 'Democratic Theory and Institutions', 1919; a hymn 'Ymwel a mi o Arglwydd da', and a poem entitled 'Afon Alun', 1924.

Letters, 1835-1840, from David Owen ('Dewi Wyn o Eifion') to Richard Humphreys (Faerdref) , Ellis Owen and James Spooner (Tremadog), together with drafts of letters by David Owen relating to Welsh literary matters.

Drafts of articles and reviews relating to Welsh grammar, literature, etc.

Autograph letters, mainly relating to English and Welsh literature and scholarship, the correspondents including John Blackwell ('Alun'), Henry Bradshaw, Lady Eleanor Butler, Sir John Hanmer, A. Hayward, W. Walsham How, Arthur James Johnes, John Jones ('Idrisyn'), W. Basil Jones, R. Harries Jones, Benjamin Hall Kennedy, Max Muller, Alfred Ollivant, Sir John Rhys, Thomas Rowland (author of A Grammar of the Welsh Language), A. H. Sayce, T. Vowler Short, Connop Thirlwall, T. F. Tout and Albert Way; with a number of 'cut-out' autographs.

'Pedeir Ceinc y Mabinogi', 'Chwedlau y Saith Doeth', 'Breuddwyd Ronabwy', 'Iarlles y Ffynnawn', 'Cyfranc Lludd a Llevelys', 'Breuddwyd Maxen Wledig', 'Ystori Geraint ab Erbin', 'Ystori Culwch ac Olwen', and 'Cedgymdeithas Amlyn ac Amic', transcribed, 1815-17, from 'Llyfr Coch Hergest' by John Jones ('Tegid') for 'Serj t.-Bosanquet', afterwards Sir John Bernard Bosanquet, with a list of the contents of 'Llyfr Coch Hergest'.

Manuscripts, estate records and papers of the Wynne family of Bodewryd, Anglesey, including records of the Bodowyr estate (Bodedern), Anglesey, and Plas Einion estate, Denbighshire, and papers of the Owen family of Penrhos, Anglesey; important Welsh literary manuscripts, legal manuscripts relating to civil and ecclesiastical law; the antiquarian collections of Edward Wynne, chancellor of Hereford, relating to Wales and to the diocese of Hereford, and part of the collection of Humphrey Humphreys, bishop of Bangor and later of Hereford; letters to Humphrey Humphreys, 1691-1709 (mainly 1705-1709); Wynne family correspondence, 1613-1816; legal papers, [17 cent.]-[18 cent.], especially relating to a lengthy action between Chancellor Edward Wynne and the Mostyn estate following the purchase by Wynne of the Bodowyr estate, 1721-1746; estate, personal and household accounts, 1603-1753; and title deeds, [13 cent.]-1864.

Corrected page proofs, 1886, of most of The text of the Mabinogion and other Welsh tales from the Red Book of Hergest, vol. I, edited by John Rhŷs and J. Gwenogvryn Evans (Oxford, 1887); together with reviews of the book, 1887.

A paper by John Ballinger on 'Some Welsh Literary curiosities'.