Okla. Stat. tit. 84 § 260
When such petition is filed, the party may proceed to make service by publication upon such defendants, in the manner following: The publication notice must, in such case, be addressed in terms, to "the heirs, executors, administrators, devisees, trustees and assigns, of __________deceased" (naming such deceased person). It shall be issued over the official signature of the clerk of the court; shall state the court in which the petition is filed, the name of the plaintiff, the above description of such defendants, and must notify the defendants thus described that they have been sued and must answer the petition filed by the plaintiff, on or before a time to be stated (which shall not be less than forty-one (41) days from the date of the first publication), or the petition will be taken as true, and judgment, the nature of which shall be stated, will be rendered accordingly. The publication must be made three (3) consecutive weeks in some newspaper authorized by law to publish notices in legal proceedings, printed in the county where the petition is filed, if there be any printed in such county, and if there be not, then in some newspaper printed in this state of general circulation in that county. A copy of the publication notice, with a copy of the petition (without exhibits), shall, within six (6) days after the first publication of the notice is made, be enclosed in an envelope and addressed to each of such devisees, grantees, or heirs at law, as are named in the petition, or his place of residence, postage prepaid, and deposited in the nearest post office, unless such place of residence is unknown to the plaintiff.
Okla. Stat. tit. 84, § 260