Okla. Stat. tit. 40, § 197.6

On and after August 1, 1965, every employer, subject to this act, shall post a notice or notices of the pertinent provisions of this act in such form as may be prescribed and furnished by the Commissioner of Labor. The notice shall be not less than eight and one-half (8 1/2) inches by eleven (11) inches in size and shall be displayed in such a manner so as to be accessible to all employees in each establishment under the control of the employer. The Commissioner, or his or her duly authorized representative, may, for the purpose of determining whether such notice has been properly posted, enter, during business hours, upon the premises of any employer subject to this act.