There are ways to keep a collection of e-books in a grid-down emergency, but many preppers prefer a dead-tree library of such things. I have a core library in that format, although most of my stuff is digital. Of course, I do have ways to use e-books more or less perpetually.
Remember – anything you buy from Amazon through any link on this site puts a commission in my pocket, at no cost to yourself, so thank you very much! Also, arf! from the Presidential Pomeranian.