Creative Commons Attribution-Share Alike 4.0 truetrue English Vial of "Undark" luminescent radium material Wikimedia username: TheBeSphereOfCourse author...
formed is painted on with a brush. It adheres firmly to any surface. English 1921 magazine advertisement for Undark, a product of the Radium Luminous Material...
_advertisement,_1921.jpg){kind=link}