Okla. Stat. tit. 63, § 2666

An ambulatory surgical center shall have a formal transfer agreement with a general hospital, as defined in Section 1-701 of Title 63 of the Oklahoma Statutes, located not more than a twenty- minute travel distance from the center, or all physicians performing surgery in the ambulatory surgical center shall have admitting privileges at a general hospital, located not more than a twenty- minute travel distance from the center.