Hello, about this Serbian (Serbien) stamp booklet？？？

Hello,
about this Serbian stamp booklet.

Put this stamp into the fold. It's not pasted. Are they booklets?
Because if it is a stamp booklet, the inner stamp edge（margin） is pasted on it.

Greetings

xiaolin

Zitat von Jean Philippe

Michel categorizes it as a booklet, but with a loose sheet.

The official post of Serbia, how do they describe them? Is it a tamp booklet?

Okay, I get their case.

Thank you!