Where can I get a list of vacuum tube prices in 1920-1950? I mean the price of vacuum tubes in that period, not the current prices for historical tubes. - Quora
Pair (2) 6U7G NU National Union radio vacuum tube ST Shoulder 6U7 - TESTED | eBay
Vintage Tested Good Blacked Out Hytron 6U7G Vacuum Tube | eBay
6U7G General Electric Audio Vacuum Tube Valve - Bangybang