Emm.. You know that some information with some time become non-relative. All the books on the site that in the top 20 is an old books(6–15 years). And you are saying that reading a 15 years old book can give something?
It’s a goof try to create profitable affiliate site, but right now recommendation system is very poor. So i think you need to get something to drink and think more about recommendation features, cause just mentions it’s not enough at all.