I've tested some methods posted on these famous ebook related forums and find the easiest way to convert VBK to PDF. Recently I have received many readers emails which inquiry if there is any way to convert VBK to PDF. People only can open these books with VitalSource Bookshelf APP which is really annoying. Most of the books downloaded from VitalSource Bookshelf are in VBK format and protected by DRM. Every now and then, students and researchers purchase textbooks from Vitalsource Bookshelf.
