Walkthrough of Matze's Great Scavenger Hunt

Step 6

I am pretty sorry, this is going to be more or less lame. But even I do have stuff to do that I like more than writing walkthroughs of the Scavenger Hunts I have put my flat-mate through.
Anyway, let me explain the last hint:
Quite some of Mathias' friends are tutors at the Technical University of Vienna. That means that they get to annoy the hell out of students, basically.
But the important thing here is that one of them is a tutor in a lecture about databases, another one is tutor in a lecture about programming, etc. - and Mathias has a book about each of those lectures.
So, the hint really narrows down the selection of books in which he has to look.
And the password riddle requires some insider knowledge, aswell. Anyway, the solution is "conit". If you're interested in what that is, you can look it up. Just search for the keywords: conit distributed systems.

Here, we have a look at Mathias' book shelf:

Believe me, in every single book is exactly one QR-Code. 58 of them are Rick Rolls:

Only one of the books (namely the PK/PP book) contains the Code which leads to the next hint:

And that is the Code leading to the next part: