This is the only legitimate route to view the content outside the app, though it comes with limitations.
By following these steps, you should be able to convert your VBK file to PDF online or using the VitalSource software. convert vbk to pdf online verified
You cannot double-click a VBK file. It is a container, not a readable document. To extract a specific text document, spreadsheet, or log file from it, you need to "mount" or "extract" it first. This is the only legitimate route to view