ACT Prep Books?

Hello!
I plan on self-studying then taking the Sept. 2015 ACT. What prep books do you recommend? I’m aiming for a score above 32.
Also, I heard that some parts of the test are being changed and that the essay will be different starting in September…could someone elaborate?
Thanks!

Search up old tests and use them for practice.

The Princeton Review 2015 is great

Barron’s rocks, actstudent.org has practice questions