O'Brien's personal papers in UCC contain more than has been previously revealed. Anyone wishing to consult this collection should email firstname.lastname@example.org . For a full catalogue of the papers, the following article is essential reading:
Philip Bull: "The William O'Brien Manuscripts in the Library of University College Cork", Journal of the Cork Historical and Archaeological Society vol. LXXV (1970), pp. 129-41
Please note that sequencing may have changed, but the box numbers still remain the same. Most boxes contain an average of four folders, with up to thirty items in each folder. Some of the material is almost illegible, but a good deal of it has been rewritten in a more legible hand before it was donated to the university, most likely by his wife Sophie.
The other collection of O'Brien papers is found in the National Library of Ireland, Dublin. A full catalogue of the papers shoudl be available on the website http://www.nli.ie/ . These papers have been recently microfilmed, and an order has been placed for these by UCC Library. Hopefully wtihin a few years all of O'Brien's personal papers should be available for consultation in UCC.