Okla. Stat. tit. 19 § 901.21
No claims shall be paid by the treasurer of said district until the same shall have been presented and allowed by the board of directors and only warrants signed by the president and countersigned by the clerk, and if the district treasurer has not sufficient money on hand to pay such warrants when presented, he shall endorse thereon "not paid for want of funds" and endorse thereon the date presented, over his signature, and from the time of such presentation until paid such warrant shall draw interest at the rate of eleven percent (11%) per annum. All claims against the district shall be verified the same as is required in the case of claims filed against the counties in this state, and the clerk of the district is hereby authorized and empowered to administer oaths to the parties verifying such claims the same as a county clerk or a notary public might do. The district treasurer shall keep a register in which he shall enter each warrant presented for payment, showing the date and amount of such warrant, to whom payable, the date of the presentation for payment, the date of payment, and the amount paid in redemption thereof, and all warrants shall be paid in the order of their presentation for payment to the district treasurer. All warrants shall be drawn and payable to the claimant or his assignee only.
Okla. Stat. tit. 19, § 901.21