Photo by Stedelijk Museum De Lakenhal
And thanks to this online gallery of the Guardian Theo van Doesburg comes to Tate Modern I can add a fourth chair known to be designed by Theo van Doesburg, shortly before his untimely death in 1931. The old photo of this chair thanks to the Netherlands Institute for Art History, which mentions the chair was for his studio in Meudon.
Right. You can see this wonderful armchair in the maison-atlier de Meudon (1931) :
http://art-zoo.com/blog/maison-atelier-theo-van-doesburg