On the subject of attributing glass lamps & I am speaking of the U.S. only here…95% of all lamp manufacturers did not manufacture the glass components of their lamps…they subcontracted with existing glass manufacturers, Cambridge, Tiffin, Heisey, Duncan, etc. whereby they sent the molds to the glass manufacturer for the pours & then had the molds & glass parts shipped back to them for assembly so identifying whom did what for whom is pretty much impossible since subcontracted job records were not kept by glass manufacturers. There were exceptions of course, Pairpoint, Aladdin, Jefferson, etc. had total manufacturing operations, metal & glass, but that’s the exception. This gives you a better idea of what you are up against when it comes to lamps in many cases as they are largely (90%+) pieces parts assembled into lamps.