Here's a couple more suggestions:

Hugh Shields, "Shamrock, Rose and Thistle: Folksinging in North Derry" Blackstaff Press (1981). This collection draws on the repertoire of singers from Magilligan Parish in the north of Co. Derry, the most famous of whom was the late Eddie Butcher. In addition to texts and airs (transcribed to reflect the actual twists of performance, thus not for the faint-hearted), Shields provides interesting notes about the songs themselves, performance practices, and the life of those who sang them.

Sean O Boyle, "The Irish Song Tradition," Gilbert Dalton, Dublin (1976). This book, which begins with an essay on Irish musical form, tonality, and metre (not all of which should be believed), contains 25 songs, six of them in Irish.

Paddy Tunney, "The Stone Fiddle: My Way to Traditional Song" Gilbert Dalton, Dublin (1979). Paddy has been much recorded; his book, which is primarily a book of reminiscences, contains texts and tunes to twenty-nine of his songs.