&quot;For everything published in 1950 the original copyright length was 28 years, but it was retroactively extended with the 1976 copyright act.&quot;<p>Not necessarily. Works published prior to 1964 have fallen into the public domain in the United States <i>unless the owner explicitly filed a copyright renewal</i>.<p>Anything published in 1964 or afterward <i>did</i> get automatic renewal and extension to the new 95 year period under the 1992 Copyright Act, so the magazines after 1964 are definitely questionable.<p>The Stanford library has a database that lets you look up the copyright status of post-1923 (before that is definitely public domain), pre-1964 works.<p><a href="https:&#x2F;&#x2F;collections.stanford.edu&#x2F;copyrightrenewals" rel="nofollow">https:&#x2F;&#x2F;collections.stanford.edu&#x2F;copyrightrenewals</a>