The poem "Ten Little Indians" was written by Septimus Winner in 1868; copyright term has expired.
As of 2021, the copyright for Agatha Christie's books has not expired. Christie's works are still protected under copyright law, and will remain so for a number of years depending on the specific publication date and jurisdiction.
There is no central repository or list for works on which copyright protection has expired.
After copyright term has expired, materials enter the public domain.
Once copyright term expires, the material enters the public domain.
Only if the copyright has expired.
"Out of print" does not equal public domain. A work is safe to use only if the copyright has expired or deliberately been placed in the public domain by the rights holder. Or if the copyright has expired and was not properly renewed.
A work that is not subject to copyright protection would be in the public domain. Examples are works of the federal government (such as NASA imagery) or works for which protection has expired.
No; protection is expired, and the works are in the public domain.
No; any protection has expired.
Works for which the term of protection has expired are in the public domain.
Most of them are old enough that copyright term would have expired, but newer translations, adaptations, and illustrations may still be protected.
Text is not copyright-free unless it was created or published so long ago that the copyright has expired, or if the text does not qualify as having sufficient "creative work of original authorship" to trigger any copyright protection.