Llythyrau, 1917-95 a heb ddyddiad, at NI. Ymhlith y gohebwyr mae Emyr Daniel, [1975] (1/223); Syr Alun Talfan Davies, 1963-77 (1/164, 178, 210, 214, 252); Aneirin Talfan Davies, heb ddyddiad (1/344); Cassie Davies, 1939, 1954 a heb ddyddiad (1/28, 90, 345-46); Gwilym Davies, 1952-3 (1/71-72, 85); Jennie Eirian Davies, 1964, [1975] a [1981] (1/173, 234, 265); y Parch. T. J. Davies, 1987-88 (1/299, 308); Alun R. Edwards, 1960-76 (1/150, 220, 235); y Fonesig Eirys Edwards, 1937 a 1976 a heb ddyddiad (1/24, 244-45, 348); Emyr Edwards, 1960 (1/151); I. Prys Edwards, 1989; Syr Ifan ab Owen Edwards, 1941-68 (1/34-35, 55, 57, 65, 114, 131, 149, 190); Owen [Edwards], 1952 a 1977 ac un heb ddyddiad (1/73, 250, 349); John Eilian, 1950 (1/54); Islwyn Ffowc Elis, 1967-68 a heb ddyddiad (1/184-85, 188, 350-51); D. Emrys Evans, 1955 (1/97); y Parch. E. Gwyndaf Evans, 1975 (1/225); Gwynfor Evans, 1974-86 (1/221, 289, 293,); y Parch. Trebor Lloyd Evans, 1947 (1/47); Syr Idris Ll. Foster, 1967 a 1979 (1/180, 259); Eirwyn George, 1977 (1/248); W. R. P. George, 1975 (1/232); Huw Griffith, 1940-42 a heb ddyddiad (1/29-31, 33, 378-80); J. Gwyn Griffiths, 1951 (1/66); R. E. Griffith, 1938-72 (1/27, 201, 203); y Parch. T. Halliwell, 1969-70 (1/191, 196); T. Rowland Hughes, 1938, 1949 a heb ddyddiad (1/26, 50, 354); Gwilym E. Humphreys, 1995 (1/343); Dafydd Ifans, 1988-89 (1/311, 314, 319); Marie James, 1983 (1/273); Syr William Jenkins, 1937 (1/22); Bedwyr Lewis Jones, heb ddyddiad (1/356-57); Bobi Jones, 1959 (1/142, 145); Dafydd Glyn Jones, 1963 (1/169); Dr Emyr Wyn Jones, 1974 a 1993 (1/216, 337); Dr Gwenan Jones, 1952-63 (1/69, 121, 171); Gwilym R. Jones, 1956 (1/108); John [Gwilym Jones], 1963 (1/163); Kitty Idwal Jones, 1975 (1/233); R. Brinley Jones, 1970-71 (1/197, 202); Tegwyn Jones, 1988 a 1994 (1/309, 342); [D.] Myrddin [Lloyd], 1953 (1/87); [Robert Lloyd], 'Llwyd o'r Bryn', 1957 (1/119); Alan Llwyd, 1991-92 (1/332-33); yr Athro Derec Llwyd Morgan, 1988 (1/306); Dyfnallt Morgan, 1955 (1/101-02); James Nicholas, 1992 (1/336); yr Esgob George Noakes, 1986 (1/297); Dyddgu [Owen], 1974-82 a heb ddyddiad (1/222, 236, 246, 261, 267, 359); Syr David Hughes Parry, 1952-63 (1/74, 95, 167); y Fonesig Haf Hughes Parry, 1932 (1/16); Syr Thomas [Parry], 1978 (1/256); Edgar Phillips ('Trefin'), 1959 (1/146-47); Richard Phillips, 1950 (1/53); Nansi Richards, 1963, ffotograff o'i hunan â cherdd 'Gwely Melangell' ar y cefn (1/172); Kate Roberts, 1958 a 1969 (1/140, 193); Dr John [Rowlands], 1968 (1/187); D. J. Williams, Abergwaun, 1950-65 (1/56, 61, 91, 126, 132, 135, 137-38, 148, 166, 175); D. J. Williams, Llanbedr, 1947 (1/48); yr Athro G. J. Williams, 1959 (1/141); yr Esgob Gwilym Owen Williams, 1953-88 (1/81, 84, 113, 258, 310); yr Athro J. E. Caerwyn Williams, 1975 (1/229); yr Athro Jac L. Williams, 1954-60 (1/93, 111-12, 134, 136, 139, 142, 152); Syr John C[ecil] Williams, 1957 (1/128); Syr T. H. Parry-Williams, 1972 (1/205); a W. D. Williams, 1959 (1/143).