Best ACT Book

I’m wondering which ACT book is best to use in preparation for it.
I have the Real ACT book but I want a book that goes through the concepts in more depth.
Any suggestions?

For Reading and English sections try Erica Meltzer’s books. She does a good job of breaking down the skills you need and writes passages and questions that are good mimics of the real test questions.
https://www.amazon.com/Complete-Guide-ACT-English-2nd/dp/1530072808?ie=UTF8&ref_=asap_bc
https://www.amazon.com/Complete-Guide-ACT-Reading/dp/1496126750?ie=UTF8&ref_=asap_bc