| A finding list of Sir James Ware's manuscripts | O'Sullivan, William, 1921-2000 | Article in Journal | | 1997 |
| A Waterford origin for the 'Codex Salmanticensis' | O'Sullivan, William, 1921-2000 | Article in Journal | | 1998 |
| Additional medieval Meath manuscripts | O'Sullivan, William, 1921-2000 | Article in Journal | | 1987 |
| An Irish 'cisiojanus' | O'Sullivan, William, 1921-2000 | Article in Journal | | 1987 |
| Binding memories of Trinity library | O'Sullivan, William, 1921-2000 | Article in Book | | 1992 |
| Ciothruadh's Yellow Book of Lecan | O'Sullivan, William, 1921-2000 | Article in Journal | | 1981 |
| Civic institutions in Cork | O'Sullivan, William, 1908-1992 | Article in Journal | | 1943 |
| Correspondence of David Rothe and James Ussher 1619-23 | O'Sullivan, William, 1921-2000 | Article in Journal | | 1994 |
| Edward Lhuyd's collection of Irish manuscripts | O'Sullivan, AnneO'Sullivan, William, 1921-2000 | Article in Journal | | 1962 |
| George Carew's Irish maps | O'Sullivan, William, 1921-2000 | Article in Journal | | 1983 |
| Insular palaeography : current state and problems | O'Sullivan, William, 1921-2000 | Article in Journal | | 1985 |
| John Madden's manuscripts | O'Sullivan, William, 1921-2000 | Article in Book | | 2000 |
| Manuscripts and palaeography | O'Sullivan, William, 1921-2000 | Article in Book | | 2005 |
| Medieval Meath manuscripts | O'Sullivan, William, 1921-2000 | Article in Journal | | 1985 |
| Notes on the scripts and make-up of the Book of Leinster | O'Sullivan, William, 1921-2000 | Article in Journal | | 1966 |
| The Book of Domhnall Ó Duibhdábhoireann, provenance and codicology | O'Sullivan, William, 1921-2000 | Article in Journal | | 1999 |
| The Book of Kells | O'Sullivan, William, 1921-2000 | Article in Book | | 1967 |
| The book of Uí Maine, formerly the book of Ó Dubhágain : scripts and structure | O'Sullivan, William, 1921-2000 | Article in Journal | | 1989 |
| The chronology of the first Anglo-Irish coinage | Dolley, MichaelO'Sullivan, William, 1908-1992 | Article in Book | | 1967 |
| The Corofin (Co. Clare) hoard : late twelfth - early thirteenth centuries | Dolley, MichaelO'Sullivan, William, 1908-1992 | Article in Journal | | 1965 |
| The donor of the Book of Kells | O'Sullivan, William, 1921-2000 | Article in Journal | | 1958 |
| The earliest Anglo-Irish coinage. | O'Sullivan, William, 1908-1992 | Monograph or Collective Volume | The Stationery Office | 1964 |
| The earliest Irish coinage | O'Sullivan, William, 1908-1992 | Article in Journal | | 1949 |
| The ecomonic history of Cork city from the earliest times to the Act of Union | O'Sullivan, William, 1908-1992 | Monograph or Collective Volume | [s.n.] | 1937 |
| The economic history of Cork City from the earliest times to the Act of Union | O'Sullivan, William, 1908-1992 | Monograph or Collective Volume | Cork University Press | 1937 |
| The eighteenth century rebinding of manuscripts | O'Sullivan, William, 1921-2000 | Article in Journal | | 1970 |
| The Irish 'remnaunt' of John Bale's manuscripts | O'Sullivan, William, 1921-2000 | Article in Book | | 1995 |
| The Irish manuscripts in Case H in Trinity College, Dublin, catalogued by Matthew Young in 1781 | O'Sullivan, William, 1921-2000 | Article in Journal | | 1976 |
| The manuscript collection of Dubhaltach Mac Fhirbhisigh | O'Sullivan, William, 1921-2000 | Article in Book | | 2000 |
| The New Manuscripts Room (1958) | O'Sullivan, William | Article in Journal | | 2012 |
| The only gold coins issued in Ireland, 1646 | O'Sullivan, William, 1908-1992 | Article in Journal | | 1965 |
| The palaeological background to the Book of Kells | O'Sullivan, William, 1921-2000 | Article in Book | | 1994 |
| The Slane manuscript of the Annals of the Four Masters | O'Sullivan, William, 1921-2000 | Article in Journal | | 1999 |
| The Strafford inquisition of County Mayo (R.I.A. Ms. 24 E 15) | | Monograph or Collective Volume | Irish Manuscripts Commission | 1958 |
| The University Press | O'Sullivan, William, 1921-2000 | Article in Journal | | 1958 |
| Three notes on Laud Misc. 610 (or the Book of Pottlerath) | O'Sullivan, AnneO'Sullivan, William, 1921-2000 | Article in Journal | | 1971 |
| Two Clogher constitutions | O'Sullivan, William, 1921-2000 | Article in Journal | | 1996 |
| Two Clogher constitutions | O'Sullivan, William, 1921-2000 | Article in Book | | 1994 |
| Ussher as a collector of manuscripts | O'Sullivan, William, 1921-2000 | Article in Journal | | 1956 |
| William Molyneux's geographical collections for Kerry | | Article in Journal | | 1971 |