You want to be looking at their affiliate program, which now appears to be under "advertising". As I recall, it's free to sign up and it works on a referral commission basis. There is nothing specifically for books, you would need to lookup the category ID for books, then you can query on that. There API is pretty extensive and has specific "fields" for different types of product.
https://affiliate-program.amazon.com/gp/advertising/api/detail/main.html
I used the Amazon API for a Facebook app at my last job called Gift-O-Matic (terrible name), that included books from Amazon as a category. The Zend Amazon lib is a good start, but I found it too verbose and rolled my own.