Question: I've seen the following bookcases while I was on holiday, and I'd like to make something similar myself. However, I'm puzzled about the structure of the bookcase.

[![enter image description here](https://i.stack.imgur.com/5AcGq.jpg)](https://i.stack.imgur.com/5AcGq.jpg)
[![enter image description here](https://i.stack.imgur.com/7Aa4W.jpg)](https://i.stack.imgur.com/7Aa4W.jpg)

It looks like the vertical side walls are not made out of a single board (as "normally" happens in a bookcase), but are multiple individual pieces, and the shelves are fixed on the top/bottom of the side boards rather than on internal face.

[![enter image description here](https://i.stack.imgur.com/V03I0.jpg)](https://i.stack.imgur.com/V03I0.jpg)

I really like the look of it, but I don't understand how the vertical bits can be fixed safely to the horizontal shelves. Do you reckon there are some metal brackets in the back to keep everything square and to give some structural stability?
How would you fix the shelves to the side boards?

Answer: 
I would use a stopped dado joint to allow the side panels to be mostly intact, but to have that exposed shelf edge on the front that you're interested in.

If it were constructed like that, it might be only the first inch of the shelf that you're seeing.

<https://www.table-saw-guide.com/dado-joint.html>
<https://canadianwoodworking.com/techniques_and_tips/stopped-dado-joint/>
The structure looks like a stacking barrister bookcase but without the glass doors. The rear panel is the key to the strength of each unit. Plus add some dowels to keep each unit centered on top of each other.