Great lamps! ......
Ivo, I doubt the writting on the label, that looks like a Z, would be a makers name. It is mos likely part of the item # or import # given to the lamp, specially if it is a paper label. Letters along with numbers are used to identify a pattern.
redgreenblue - Can you post a photo of the label?
We might be able to lknow more about the lamps from it.