I tried to get an adapter for the socket and was unable to find one that fit. It's threaded (not bayonet) and it's not the French E14 thread or American C6, C7, or C9. The lamp harp is a bit wobbly but the lamp itself is amazing. Well worth the restoration for someone that has the time to track down rare German bulbs or whatever.
Rather small at just 13 tall. The item "Antique vtg Art Nouveau Deutsches Reichsgebrauchsmuster lamp jeweled shade" is in sale since Wednesday, August 26, 2020. This item is in the category "Antiques\Architectural & Garden\Chandeliers, Sconces & Lighting Fixtures". The seller is "hardtofindhouseparts" and is located in Portland, Oregon.
This item can be shipped to United States.