Mo. Rev. Stat. § 349.065

The corporation may from time to time issue renewal notes or refund any bonds by the issuance of refunding bonds, whether the bonds to be refunded have or have not matured, and to issue bonds partially to refund bonds then outstanding and partially for any other purpose. Renewal notes or refunding bonds may be sold at public or private sale and the proceeds applied to the purchase, redemption, or payment of the notes or bonds to be refunded.