A graphical interface for creating and reading QR codes.
QtQR can read QR codes from image files or from a webcam. It is able to recognise a number of specific types of QR code including web links, email addresses/messages, SMS messages and telephone numbers.
You could potentially scan the QR code from the book using a webcam. If you do this, ensure there is enough light and that you are holding the QR code flat and still. You will see a window with the webcam input on the screen. Wait until green dots appear then close the window and QtQR will tell you what was contained in the QR code.
As of Bionic (18.04), QtQR is available on Ubuntu by running:
sudo apt install qtqr
You can also install newer versions of QtQR by adding the PPA ppa:qr-tools-developers/qr-tools-stable and installing the package