Okla. Stat. tit. 84 § 253
Upon the filing of such petition the judge of the district court shall make an order fixing a day for the hearing of said petition, not less than six nor more than ten (10) weeks from the time of making such order, and directing all the heirs of such deceased person and record claimant to lands or any part thereof of which said decedent died seized to appear before the court at the time and place specified, and to submit to the court evidence that is competent to establish heirship of such deceased person. The court shall cause notice of such hearing to be given by serving a copy of said notice on the known heirs and record claimants of said decedent's estate in the manner and within the time as provided for service of summons in civil actions in the district court. The service on unknown heirs and unknown claimants shall be had in the same manner as is now provided for the service of summons in civil actions in the district court for nonresident defendants. The hearing shall be had on the date fixed by the court, except continuances may be had for good cause shown, as in civil actions.
Okla. Stat. tit. 84, § 253