Anonymous documents published before January 1st, 1923 are in the public domain in the following jurisdictions:
- the United States, where any document published before January 1st, 1923 is in the public domain;
- the European Union, where the copyrights for an anonymous work expire 70 years after its first publication;
- Japan, where the copyrights for an anonymous work expire 50 years after its first publication.
Advertising material published by a company follows the same rules as anonymous documents, unless (a) it is explicitly signed by an individual or (b) some individual later claimed to be the original author.
- Copyright Term and the Public Domain in the United States, 1 January 2007, by Peter B. Hirtle.
- Council Directive 93/98/EEC of 29 October 1993 harmonizing the term of protection of copyright and certain related rights, art.1.
- Copyright law of Japan (from the CRIC website), chapter II, section 4.