A small addition to this post from a catalogue.
(Corrected by a note from Alex: these lamps existed in the GDR in the 1950s.)
![](https://www.lighting-gallery.net/proxy.php?request=http%3A%2F%2Fwww.bremsenbude.de%2Fleuchten%2FSIERAY_electric_discharge_lamps_catalogue_may_1937_21.jpg&hash=0ba9ad16833080bbf0e3bb74ab06920c45ef7822)
Source: SIERAY-catalogue, May 1937
![](https://www.lighting-gallery.net/proxy.php?request=http%3A%2F%2Fwww.bremsenbude.de%2Fleuchten%2FSIERAY_electric_discharge_lamps_catalogue_may_1937_22.jpg&hash=b745126ae551913ace6cc781796ae8aba2ca6532)
Source: SIERAY-catalogue, May 1937
![](https://www.lighting-gallery.net/proxy.php?request=http%3A%2F%2Fwww.bremsenbude.de%2Fleuchten%2FSIERAY_electric_discharge_lamps_catalogue_may_1937_23.jpg&hash=fffdbff76b43d8c8ed8594f36ccde5a19c106528)
Source: SIERAY-catalogue, May 1937
I didn't know there were different colors.