Maybe due to my Eidetic Memory in ESO, I have a tendency to click a book enough to get credit for reading it and figure I'll read it later at my leisure. So I didn't think to screenshot the books and papers in the story instances, especially as they looked like the new books in Istan that we get physical copies of. I realized afterward that I can't go back to read them until I replay the instance, at which point I will have the same problem I did on the first run: tons of aggro attacking me while I try to read without getting downed.
Any chance we'll soon(tm) or at least eventually get a UI library that holds copies of all the in game books/scrolls/letters we've read? A well organized and searchable one, of course