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This advertisement did not have a copyright notice and is in the public domain.

From the US Copyright Office Circular 3. Page 3, Contributions to Collective Works. (A magazine is a "collective work.")

A notice for the collective work will not serve as the notice for advertisements inserted on behalf of persons other than the copyright owner of the collective work. These advertisements should each bear a separate notice in the name of the copyright owner of the advertisement.

Furthermore Passport Corporation failed to register appropriately within 5 years as required by law.