21 September (United States of America ) within release American Inventors Issue goes into circulation Stamp Charles Steinmetz and Curve on Graph face value 20 United States cent
Stamp Charles Steinmetz and Curve on Graph in catalogues | |
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Michel: | Mi:US 1653 |
Stamp Number: | Sn:US 2055 |
Stamp is square format.
Also in the issue American Inventors Issue: