I have got a kindle tablet. I have connected to the School online network to read some math textbooks. Those were in PDF format. I transferred those files to Kindle. This device can open those files but it losed format. It cannot render algebra formulas and texts. Sometimes the general format is also gibberish. I tried the Calibre, to send pdf directly via amazonís conversion service but it didnít work. Does anyone know how to convert pdf's without losing format to .mobi or any Kindle readable format?