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.
Works published in 1933 would have had to renew their copyright in either 1960 or 1961, i.e. at least 27 years after it was first published / registered but not later than in the 28th year. As it was not renewed, it entered the public domain on .