Okla. Stat. tit. 68, § 1801

Cooperative, nonprofit, membership corporations organized or operating under the provisions of the Rural Electric Cooperative Act, Senate Bill No. 141, as enacted by the Seventeenth Oklahoma Legislature, for the generation, transmission and distribution of electric energy, are hereby expressly classified for purposes of taxation. Such corporations are hereinafter referred to as "Cooperatives". Laws 1943, p. 178, § 1; Laws 1965, c. 215, § 1.