Okla. Stat. tit. 11, § 11-32-113: Apportionment of costs - Assessing ordinance -

Limitation on suits.

The portion of the cost of any improvement to be assessed

against the property in the improvement district shall be

apportioned against the property in accordance with the special

benefits accruing thereto by reason of the improvement. The cost

may be assessed equally per front foot or per square foot against

all lots and pieces of land within the improvement district or the

cost may be determined and fixed on the basis of any other

reasonable assessment plan which will result in imposing

substantially equal burdens or shares of the cost upon property

similary benefited. The governing body shall determine the final

apportionment of costs of the improvement and shall levy, by

ordinance, assessments in accordance with the apportionment against

the property liable therefor. No suit shall be maintained in any

court to enjoin or in any way contest the validity of any special

assessment for the cost of acquiring or improving parking stations

unless the same be instituted and summons served within thirty (30)

days after the date of the publication of the ordinance levying the

assessment.