Okla. Stat. tit. 68, § 2358.5A

A. All bonds, notes, debentures, evidences of indebtedness, lease purchase agreements, certificates of participation, commercial paper, or other obligations issued by the State of Oklahoma, the Oklahoma Capitol Improvement Authority, the Oklahoma Municipal Power Authority, the Oklahoma Student Loan Authority, and the Oklahoma Transportation Authority, the income therefrom, including, without limitation, any profit made on the sale thereof, and the transfer thereof, including, without limitation, estate or inheritance taxes, shall at all times be free from taxation within this state. B. The provisions of this section shall be supplemental to, and not limiting or restrictive of, any law involving the taxation of such obligations within the State of Oklahoma.