There are a few books you should purchase over and above the books the school requires.
Do your research on NCLEX-RN EXAMINATION BOOKS
A VERY GOOD ONE IS
SAUNDERS
Comprehensive Review for the NCLEX-RN EXAMINATION.
(This book is broken down by subject) and is one of the best I have seen.
I have heard Kaplan NCLEX is good also. The Kaplan actually gives you test taking tips.
Do not be afraid to purchase more than one NCLEX book, they will save your life in nursing school.
