| 'An overriding providence' : the life and ministry of Tresham Dames Gregg (1800-81) | Crawford, John, 1953-2011 | Article in Book | Four Courts Press | 2006 |
| A charge delivered to the clergy of the united dioceses of Cork, Cloyne, and Ross at the ordinary visitation, October 1867 | Gregg, John | Monograph or Collective Volume | Hodges, Smith | 1867 |
| A charge delivered to the clergy of the united dioceses of Cork, Cloyne, and Ross at the ordinary visitation, October 1882 | Gregg, Robert S. | Monograph or Collective Volume | George Herbert | 1882 |
| A charge delivered to the clergy of the united dioceses of Cork, Cloyne, and Ross, at his primary visitation, in September, 1863 | Gregg, John | Monograph or Collective Volume | William Curry | 1863 |
| A charge delivered to the clergy of the united dioceses of Cork, Cloyne, and Ross, at the ordinary visitation, October 1866 | Gregg, John | Monograph or Collective Volume | Hodges, Smith | 1866 |
| A comment on the life and work of Professor Gregg Wilson (1865-1951) of Queen's College and University Belfast and the links between professional and amateur naturalists in the late nineteenth and early twentieth centuries | Baker, R.A.Bayliss, R.A. | Article in Journal | | 2003 |
| A guide to Ireland's railway heritage | Ryan, GreggShare, Bernard | Monograph or Collective Volume | Iarnród Éireann | 2002 |
| De scriptoribus Hiberniae. Libri duo | Ware, James | Monograph or Collective Volume | Gregg | 1966 |
| Evangelicalism, the Church of Ireland and the anti-Catholicism in the life and thought of Rev. Tresham Dames Gregg (1800-81) | Connell, Paul. M. | Thesis | | 2007 |
| Hibernia Dominicana; sive, historia provinciae Hiberniae Ordinis Praedicatorum | Burke, Thomas, O.P., bishop of Ossory, c.1709-1776
| Monograph or Collective Volume | Gregg | 1970 |
| John Allen Fitzgerald Gregg, archbishop | Seaver, George | Monograph or Collective Volume | Faith P.|Hodges Figgis | 1963 |
| King Charles I | Gregg, Pauline | Monograph or Collective Volume | | 1981 |
| Letter of James Murray, of New York, to Rev. Baptist Boyd, of County Tyrone, Ireland, reprinted from the Pennsylvania Gazette, Oct. 27, 1737. | | Monograph or Collective Volume | | 1925 |
| Materials for the history of the Franciscan province of Ireland A.D. 1230-1450 | | Monograph or Collective Volume | Gregg Press | 1967 |
| Remonstrantia Hibernorum contra Louvanienses, 1665 | Caron, Redmond
| Monograph or Collective Volume | Gregg | 1970 |
| Scots language in Ulster | Gregg, Robert J.Montgomery, Michael B. | Article in Book | | 1997 |
| Setting a place at the table : ending insurgencies through the political process | Gregg, Heather S. | Article in Journal | | 2011 |
| St. Patrick's Church, Ballymena : centenary sounvenir of consecration, 1855-1955 | Craig, C. H. B., Rev. | Monograph or Collective Volume | [St Patrick's Church] | 1955 |
| Talk given to Coleraine Historical Society on 17 November 2009 | Gregg, Harry | Article in Journal | | 2010 |
| The "German" Smyths of Carlow county | Smyth, M. Gregg | Article in Journal | | 1995 |
| The church visible and one : a sermon preached before the general synod, May 1932 | Gregg, J. A. F. | Article in Book | | 2004 |
| The episcopal succession in England, Scotland and Ireland, A.D. 1400 to 1875 | Brady, W. Maziere | Monograph or Collective Volume | Gregg | 1971 |
| The Fallen remembered in St. Peter's | Onions, Mark | Article in Journal | | 2014 |
| The population of Ireland before the nineteenth century | | Monograph or Collective Volume | Gregg | 1973 |
| The red hand and the Kiwi | Hopkins, Gregg | Article in Journal | | 1986 |
| The Scotch-Irish dialect boundaries in the province of Ulster | Gregg, Robert J. | Monograph or Collective Volume | Canadian Federation for the Humanities | 1985 |
| The works : celebrating 150 years of Inchicore Works | Ryan, Gregg | Monograph or Collective Volume | Gregg Ryan | 1996 |