"or, sometimes, to two or three years"..

That explains my findings. Yes i have come to know that this obscure(?) system was first used by ICA that later became part of Zeiss Ikon (the net is full of a wikipedia quote about it but no one explains the system or links to info about it). So even if it can differ on a couple of years, it looks to be a pre-war camera. From all my browsing around i feel it is around 1937 to 1940. Yet another sign of pre-war is that the Nettar lens is not coated. I will come back with some pictures of the camera.