Last year I got an iPad, my first Apple device (I needed ForeFlight for flying, and it's only available for iPad). I downloaded a few manuals for ForeFlight, which apparently went to Books. I pulled one up in Books, spent a few minutes glancing and things, and spent the next 15 minutes trying to figure out how to get out of the current book back to my list of books. Finally took it to my wife (a long-time Apple fan), and it took her about 3 minutes of tapping and dragging various places. In the end, neither of us knew how we did it.