Okla. Stat. tit. 12, § 12-615
Appointment of referee
In all cases of reference, the parties, except when an infant
may be a party, may agree upon a suitable person or persons, not
exceeding three, and the reference shall be ordered accordingly; and
if the parties do not agree, the court shall appoint one or more
referees, not exceeding three, who shall be free from exception.
R.L. 1910, § 5021.