William W. Kibler, Grover A Zinn. A one-volume reference that focuses on France. The Oxford Companion to Irish history . Oxford University Press, 1998. Several thousand brief entries in alphabetical order for events and people in Irish history.
Coverage is extensive, but necessarily superficial.
No bibliographies or index. The Oxford Companion to Irish literature . Oxford University Press, 1996. Helpful volume of several thousand brief entries of authors, movements and specific works and genres. No bibliographies and few cross references, but very extensive coverage of the full range of Irish literature.