Thanks guys for replying!
I installed the “Kaya QR code” plugin, and its very easy to use, it generates a unique QR code for each Pods entry by inserting:
[kaya_qrcode title_align="alignnone" ecclevel="L" align="alignnone"]
in the Pods template.
However, the permalinks dont seem to be using Post ID’s. For example, the page I created to “catalog” my books has the following permalink
https://localserver/wordpress/?page_id=157
while an entry (for example Sapiens) has
https://localserver/wordpress/?book=sapiens-a-brief-history-of-humankind
The URL seems to use the post title and not the Post ID…. Am I doing something wrong with the way I create entries (posts)?