Русско-англо-русский юридический словарь

A written contract as the name suggests, is a contract whose terms have been reduced to writing. Written contracts are also commonly signed. However, a written contract may consist of an exchange of correspondence, a letter written by the promisee and assented to by the promisor without signature, or even a memorandum or printed document not signed by either party. (definitions.uslegal.com)

The Secretary of State’s office will verify the notary public’s or other notarizing official’s signature by placing an apostille on the document. (website of U.S. Embassy in Russia)

ARTICLE 14. Signature and Entry into Force. 1. This Protocol shall be open for signature by the member States of the Council of Europe which are a Party to or have signed the Convention. (Third Additional Protocol to the European Convention on Extradition)

This Agreement will become effective when one or more counterparts have been signed by each of the parties and delivered to the other parties, which delivery may be made by exchange of copies of the signature page by facsimile or other electronic transmission. (Law Insider)