I'm a new member here. I have a teaching book that I want to convert to pdf and share with you guys here. However after remove the DRM, the file is not readable or convertible by any programs (i tried Calibre, Epub converters, online converters..). The strange thing is that Kindle app still can read that De-DRM file normally...

I upload the file here: https://www.mediafire.com/?ycxp1s9aws0q2i1

If anyone know how to convert it into a readable file, please advise.

Thank you