Okla. Stat. tit. 25, § 1605
In a proceeding under this act a written, printed, or visual communication, advertisement, or other form of publication, or written inquiry, or other document purporting to have been made by a person is prima facie evidence that it was authorized by him.
Laws 1968, SB 367, c. 388, § 605, emerg. eff. May 17, 1968.