I've a friend looking for any literature on Irish Mythological Cycles (I nor anybody i've asked didn't know anything about them!) as she is doing a thesis on Celtic Heritage.

the Mythological Cycle;
the Ulster (or Red Branch) Cycle;
the Fenian (or Ossianic) Cycle;
and the Historical (or Kings') Cycle

She is looking for books of an academic nature rather than simply containing the myths. Does anybody know of anything that could help? As she lives in Poland she doesn't have access to Irish Libraries to see what they have to offer so would need to buy something.