“The Kindle Fire uses the .mobi file format for its e-books, and e-books in the .mobi format can be found in thousands of places all over the internet, some paid, and others free. There are also millions of books in the popular E-PUB format used by Sony and by Google, and there are free converters readily available from hundreds of sources on the web that will convert files from the E-PUB format into the .mobi format used by all Amazon Kindles.”