For Carolan's life and music, the authoritative work is Donal O'Sullivan's book
Carolan; the life, times, and music of an Irish harper. Originally published in 2 volumes by Routledge and Paul, London, in 1958, it was reprinted by Celtic Music, Louth, England (1991); A new single-volume edition is available from Ossian, Cork (2001).
Gráinne Yeats's online article The Rediscovery of Carolan is worth reading.
Ordering instructions: I carry a number of Gaelic harp books and CDs in stock at the Emporium. You can order them from right here on the listings pages by selecting your postage rate and clicking "add to cart". Postage will be charged at the rate shown and calculated by the shopping cart. Alternatively you can save a bit on postage if you call or email me to discuss what you want - I am happy to try and source out-of-print or hard-to-find items not currently in stock. Go to the Emporium homepage for more details.
I also will buy secondhand copies of these and other related items. Contact me with details of what you have and we can discuss terms.