Okla. Stat. tit. 40, § 2-605
The parties shall be promptly notified of such referee's decision and shall be furnished with a copy of the decision, including the findings and conclusions in support thereof. Such decision shall be final unless, within ten (10) days after the date of mailing of notice thereof to the parties' last-known addresses, or, in the absence of such mailing, within ten (10) days after the delivery of such notice, further review before the Board of Review is initiated pursuant to Section 40-2-606.
Laws 1980, SB 637, c. 323, § 2-605, eff. October 1, 1980.