4 beautiful chairs but who is the designer?  

If you look at the underside...
If you look at the underside of the back is it plywood?

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What kind of nails are used to fix the papercord underneath the seat?

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The back looks like solid teak.
Thanks for your support.

Well that is interesting. ...
Well that is interesting.
The danes interpreted this general design a few times. I bumped into some others just like these on Lauritz. And there are quite a few interpretations of this design.
The staples holding on the cord don't bode well. The only time I've ever seen that on pedigree chairs was some of the Arne Hovmand Olsen for Mogens Kold chairs that look sort of similar to these. Those chairs had cane seats which were replaced with cord that was stapled on.
So unless you see indications that the cording was re-done from cane or an upholstered seat, I would guess it is a safe bet they have no pedigree and are pretty late productions. Feel free to prove me wrong. In fact I'd love to be proven wrong, because they are nice looking chairs.