Idioms with BOOK

by the book
exactly according to rules or instructions
We were careful to do everything by the book.

an open book
a person or thing that is easy to understand or learn about
His life is an open book. He has nothing to hide.

a closed book
a person or thing that is difficult to understand
Chemistry is a closed book to me.

hit the books
to study
I need to hit the books. I have an exam tomorrow.

cook the books
to change facts or figures dishonestly or illegally
Officials at the bank were found to have cooked the books.