Mo. Rev. Stat. § 100.140: Sinking fund for revenue bonds.

At or before the issuance of the revenue bonds the governing body shall, by ordinance, create a sinking fund for the payment of the bonds and the interest thereon, and shall set aside and pledge a sufficient amount of the revenues of the project to be paid into the sinking fund at intervals to be determined by ordinance prior to the issuance of the bonds, for

(1) The interest upon the bonds as such interest shall fall due;

(2) The necessary fiscal agent charges for paying bonds and interest; and

(3) The payment of the bonds as they fall due or if all of the bonds mature at the same time, the proper maintenance of a sinking fund sufficient for their payment at maturity.