System for validating mail by postal certification
United States Patent 3221980
US Patent References:
/0932090.html
- - 0932090

Removable opaque insert for envelopes
- - 1962921

Mailing envelope
- - 2794590


Inventors:
Dave, Mercur
Publication Date:
12/07/1965
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Assignee:
Dave, Mercur
Primary Class:
229/71
International Classes:
B42D15/08