THE manuscript collections listed below have been extensively consulted in the preparation of this work. They will be referred to by the following abbreviations:
| Abbreviation | Collection | Description of materials |
| BM Add. MSS. | British Museum Additional Manuscripts | [Gladstone Collection] (followed by volume and folio number). |
| CUL Add. MSS. | Cambridge University Library Additional Manuscripts | [Acton Papers] (followed by catalogue number) |
| Downside MSS. | Papers in the Library of Downside Abbey, | collected by Cardinal Gasquet, chiefly letters of Lord Acton to Richard Simpson and T. F. Wetherell. |
| Manning MSS. | Church of St. Mary of the Angels, Bayswater, London | Papers of Cardinal Manning in the possession of the Oblates of St. Charles |
| Newman MSS. | Oratory, Birmingham | Papers of Cardinal Newman |
| Westminster Archives | Archives of the Archdiocese of Westminster | MSS 1847-1865. |
| Woodruff MSS. | Mr. Douglas Woodruff | Correspondence of Lord Acton Includes that wiith with J. J. I. von Döllinger, being edited for publication by Abbé Victor Conzemius; my translation from the German. |
Last modified 15 September 2001