Buy directly from the publisher Golden Key here
Other Irish online stockists:
Kenny's in Galway ship free worldwide here
O'Mahony's in Limerick here
Tara Books in Kinvara, Co Galway here
Alan Hanna in Rathmines, D6 here
UK, Europe or other International:
Amazon here
Waterstones here
The Book Depository here
Gardners here (wholesale)
Libraries:
For Libraries it can be obtained from International Educational Services in Leixlip or Alan Hanna in Rathmines, D6