You can also add your books for the cloud and read them anywhere. That gives you an extremely good storage alternative which you can entry on any system with an internet connection. Some other options involve book rentals, a fast skim method, and a quick bookmark function. The app is https://colab.research.google.com/drive/1VbrsbAZmqL9YrwPm2zVDqcFixwwE42z9?hl=km