Okla. Stat. tit. 68, § 68-209: Notice to Commission's attorney before judicial hearing -

Costs.

No court of this state shall hear or try any case in which the

Tax Commission is a party plaintiff, defendant or intervener, until

it has been made to appear to said court that notice of the time and

place of said hearing has been given by registered or certified

mail, for at least ten (10) days, to the attorney of the Tax

Commission. Such notice shall be given by the court clerk and the

cost thereof taxed as court costs in the case.