It is closest to the chair I found online a danish design(though this has arms) http://www.collectorsweekly.com/stories/161372-i-think-they-are-a-find-d... Check for the chair design
The shape reminds me of a number of designs by Montis, especially the Geraldine chair by Gerard van den Berg. It's not that, though. Might be worth investigating old Montis catalogues though? They're Dutch, too.
https://www.montis.nl/en/designer/gerard-van-den-berg/
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