Can't find or download iBooks app.

Hello! I'm trying to get iBooks onto my iPad. It's running version 10.1.1. When I try to sync audiobooks from iTunes onto my iPad it tells me that I can't sync audiobooks without the iBooks app, however when I search the store I can't find the app - even when searching from within iTunes for desktop - iBooks does not even appear in the store! With my older iPad, at least it tells me "must run at least 7.x to install this app". I can't even find iBooks! Help!