Papurau'r Parch. Lewis Valentine, 1874-1983, yn cynnwys gohebiaeth gyffredinol, 1916-1983; llythyrau oddi wrth Saunders Lewis, [1926]-1983; llythyrau oddi wrth D. J. Williams, 1930-1969; llythyrau oddi wrth Kate Roberts, 1937-1976; llythyrau'n ymwneud â'r Ysgol Fomio a charchariad Lewis Valentine, 1936-1937; dyddiaduron rhyfel,1916-1919; anerchiadau gan Valentine ac eraill, 1930-1972; a phapurau amrywiol a gasglwyd gan Valentine, 1874-1980. = Papers of the Rev. Lewis Valentine, 1874-1983, comprising general correspondence, 1916-1983; letters from Saunders Lewis, [1926]-1983; letters from D. J. Williams, 1930-1969; letters from Kate Roberts, 1936-1976; letters relating to the Bombing School and Lewis Valentine's imprisonment, 1936-1937; war diaries, 1916-1919; addresses by Valentine and others, 1930-1972; and miscelleneous papers collected by Valentine, 1874-1980.

Papurau Frank Jones, Llanrwst, sir Gaernarfon,1932-1944, yn cynnwys llyfr nodiadau'n ymwneud â'r ymgyrch yn y 1930au i gael ffurflenni'r Dreth Incwm yn Gymraeg, a'i ddyddiadur, 17 Ionawr 1941-8 Medi 1942, yn mynegi ei argraffiadau o gyfnod rhyfel fel heddychwr a chenedlaetholwr; gohebiaeth,1936-1944, yn cynnwys ei gais, 1940, i gael ei gofrestru fel gwrthwynebydd cydwybodol ar sail bod yn genedlaetholwr o Gymro. = Papers of Frank Jones, Llanrwst, Caernarfonshire, 1932-1944, including a notebook relating to the campaign for Income Tax forms in Welsh in the 1930s, and his diary, 17 January 1941-8 September 1942, containing his impressions of war as a pacifist and nationalist; correspondence, 1936-1944, including his application, 1940, to be registered as a conscientious objector on the grounds of being a Welsh nationalist.

Welsh Republican Movement and Plaid Cymru papers collected by Cliff Bere, 1940-1973, including correspondence, [c. 1947]-1965; membership forms and subscriptions, [c. 1948]-1957; constitution, meetings and reports, 1949-1952; newspaper cuttings, 1949-1991; political and personal correspondence, 1933-1997; papers relating to Plaid Cymru, [c. 1949]-1996, including the Parliament for Wales Campaign, Cymdeithas yr Iaith (Welsh Language Society) campaign for bilingual road signs, 1971; 'Cofiwn', the National Commemoration Association, 1976-1987; the Welsh Socialist Republican Movement (Mudiad Gweriniaethol Sosialaidd Cymru) 1975-1985; Cymdeithas Cyfamod y Cymry Rhydd (the Society of the Covenant of the Free Welsh) 1986-1994; Cardiff City Planning Department, 1965-1982; Harri Webb papers, 1949-1996; Eurig ap Gwilym [d. 1988], 1976-1988; papers relating to holiday homes arson campaign and Bere's arrest, 1980-1982; Yr Undeb Celtaidd /The Celtic League, 1988-1993; the Free Wales Army, 1993-1998; unpublished drafts of articles, 1934-1996; various journals and pamphlets, [c. 1946]-1976; newspapers cuttings, 1946-1997; undated translations of pamphlets published by the National Museum of Wales; papers, 1984-1998, relating to his publications, and other printed ephemera, 1935-1956.

Papers of Harri Webb, [c. 1919]-1995, including poetry, 1942-1989; reviews and reader's reports, 1974-1986; correspondence with publishers, broadcasters and editors relating to Webb's work, 1949-1995; correspondence from literary and artistic figures, [1940s]-1983; political correspondence, 1964-1974; political press cuttings, 1952-1981; papers relating to Plaid Cymru, 1961-1978, and Scottish politics, 1967-1969; and personal papers, [c. 1919]-1984.

A collection of Harri Webb's diaries. This group remains uncatalogued.