Works published prior to Jan 1, 1923, that had a
enter the public domain in 75 years. ALL works published prior to 1930
are now in the public domain. If they didn't have a copyright notice,
then they immediately entered the public domain.
The Sonny Bono extension changed this period to 95 years. The 75 year
period now applies only to libraries and archives for works that are not
available at a reasonable price.
The failure to include a copyright notice voided the copyright for works
published before 1989.
However, if a work was NOT published prior to 1930 -
for instance, if
a work was discovered after the author's death and published in 1955,
then it is subject to to the 1978 copyright law of 28 years from the
date of publication plus potential renewal of up to 47 more years.
The need to have been renewed only applies to works published before 1964.
So... if Harvard published the poems in 1955, and they
previously published, then they can potentially have a copyright that
lasts until 2030.
Yes, but the copyright had to be renewed in 1983
Republishing does not generate a new copyright,
although new materials
included in the republished works, such as commentary, are protected.
This is a key point.