We are two students, who are using Calibre app, and are very happy with it. We are using it every day, and are very happy because it is very useful for our studies. We are also excited that it is available worldwide, and that it is free to use for everyone! We also publish useful guides, the latest news, update notes and more about Calibre app. We are very excited about this app because it is not only free, but it is also very useful for our studies!