| From Strongbow to Piers and Margaret Butler: Kilkenny Castle in the middle ages | McEvoy, Elizabeth | Thesis | | 1998 |
| Inaugural address delivered by the right rev. Dr. Moran, bishop of Ossory, at the first meeting of the Ossory Archaeological Society, 7th January, 1874 | Moran, Patrick Francis, cardinal, 1830–1911 | Article in Journal | | 1879 |
| Margaret Fitzgerald wife of Piers Butler 8th earl of Ormond and 1st earl of Ossory | Kehoe, Imelda | Article in Journal | | 1991 |
| Miscellanea. 1. A bench from the hourehold of Piers Ruadh, 8th earl of Ormond | Hogg, Ulrike | Article in Journal | | 2012 |
| Red Piers of Ormond | Butler, George | Article in Journal | | 1968 |