Have you come across the problem of converting the files? I want to suggest to help you a great website where you can download free converters of various formats!
The site http://converton.net/ you can read articles like:
- How convert PDF to DOC?
- How convert ePub to TXT?
- How transform DJVU to PDF?
- How to get a picture from PDF?
In each article there is a link to download a free converter.