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| Title | Certificate of Mailing |
| FormNumber | 3817 |
| Revision | 9-37 |
| Division | |
| WhereUsed | Provides proof of mailing.1915-1929 4th class only; since 1929 all classes |
| EKU | 1937 ASW |
| LKU | 2007 ASW |
| Notes | Wawrukiewicz, Domestic ch. 44 (1531 possible forerunner |
| Source | SS |
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