Progress in Electronics issue of United States
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Short desc: Progress in Electronics
Issuer: United States Date: 7/10/1973 Occasion: unset Consists of 4 stamps: (See stamps as list) 6c dt=electronics progress d=Marconi spark coil & gap 8c dt=electronics progress d=printed circuit board 15c dt=electronics progress d=early microphone, radio tube, TV camera tube, radio speaker airmail 11c d=two De Forest audions All are perf=11 Record of changes |
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