I want to study from BPP books and I will appear in exam for F2 only in December 2015 or may be October 2015 and I am confused to buy the book which book I should Buy that if I sit in October 2015 exam is also valid and if I sit in December 2015 exam is also valid, Is this too Different book and topic or is this okay if I buy valid till June 2015 and I sit in December 2015 exam so still I can pass the exam from the study text valid till June 2015 ?