These are a few off the top of my head:

Narrative Singing in Ireland by Hugh Shields

Social History of Irish Traditional Music by S.C. Hamilton

Irish Traditional Music by Ciaran Carson (this is a small Appletree (? I think) Press book which gives a wonderful intro to the the music.

The first two are pretty substantial reading, the last one is a simple, easy to read intro. Without knowing what you want the information for, it is hard to recommend books--if would you please let us know what you are looking for, we can better direct you to the right books!