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.
This image was originally posted to Flickr by San Diego Air & Space Museum Archives at https://flickr.com/photos/49487266@N07/22715668655. It was reviewed on 2017-01-27 22:57:21 by FlickreviewR, who found it to be licensed under the terms of the No known copyright restrictions, which is compatible with the Commons. It is, however, not the same license as given above, and it is unknown whether that license ever was valid.