Some or all works by this author are in the public domain in the United States because they are legally published within the United States (or the United Nations Headquarters in New York subject to Section 7 of the United States Headquarters Agreement) before 1964, and copyright was not renewed.

• For Class A renewals records (books only) published between 1923 and 1963, check the Stanford University Copyright Renewal Database.
• For other renewal records of publications between 1922–1950 see the University of Pennsylvania copyright records scans.
• For all records since 1978, search the U.S. Copyright Office records.

It is imperative that contributors search the renewal databases and ascertain that there is no evidence of a copyright renewal before using this license. Failure to do so will result in the deletion of the work as a copyright violation.

These works may still be copyrighted in jurisdictions not applying the rule of the shorter term to U.S. works.