Okla. Stat. tit. 11, § 11-37-210: Special attorneys, auditors or consulting engineers

The municipal body may contract for the services of special

attorneys, auditors or consulting engineers to make the necessary

surveys, and prepare plans, plats, profiles, estimates and all other

details for the work of improvements and to supervise the work. Any

such consulting engineer shall be a person, firm or corporation,

resident in the State of Oklahoma, and duly registered as an

engineer in the State of Oklahoma. A consulting engineer may be

employed also to furnish the necessary advertising, printing,

transcripts, legal fees, preparation of assessment rolls, and such

other expense as may be necessary. The municipality shall provide

for the payment of such services and expenses from the assessments

to be levied as part of the cost of such improvments, except as

otherwise provided.