Amazon.com: UltraPro Porcelain Light Socket with Pull Chain Light Fixture, Light Bulb Socket, Medium Base, Indoor Lighting, Mount on 3-1/4” or 4” Box, 250VAC/660W, UL Listed, White, 18303 : Home & Kitchen
2 Outlet Light Socket Adapter, E26 Bulb Socket to Outlet Splitter,Converts Medium Screw Socket into a Socket with Two outlets,Polarized Outlet,with Pull Chain Switch. UL Listed, White (2-Pack) - Amazon.com
Leviton Plastic Pull-Chain Lampholder R50-08827-CW4 - The Home Depot