Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.
Uploaded a work by Riddle Airlines from This is an uncredited photo from the 13th page of a document from 1960 published without a copyright notice. The document is within this file: https://n2t.net/ark:/65665/pg2ed05cebb-20ab-49b1-a0ec-5359e89409b7 The document, which is a preliminary prospectus, starts on the 40th image. The photo is on the 52nd image (the 13th page of the document). with UploadWizard