Bibliographic databases gather links to and citations for scholarly articles, and many also provide the articles themselves. The Hesburgh Library provides a link between article citations and other databases that might contain the article.
You may find books on the Hesburgh Library shelves, or apply through the Interlibrary Loan system for books in other libraries. If you wish to browse, these are the most useful areas for Irish: PB (Irish language and literature), DA (Irish history) and GR (folklore).
These resources will help you find unpublished theses and dissertations, which present an author's research and findings as part of their degree candidacy or professional qualification.