Book recommendations for ipcc

Lavanya.1 (Student Others) (151 Points)

15 August 2014  
I am going to appear for IPCC., May 2015 . But right now, all books are available only for NOV '14 Attempt. Should I buy these books? if I buy them, would there be any big difference , between Nov '14 books and May '15 books. Or else wait for December or January, to buy may'15 books. But that would be too late. Plz suggest what should I do?