Mo. Rev. Stat. § 234.270: Bonds, how sold or exchanged.

Toll bridge revenue refunding bonds issued under the provisions of sections 234.210 to 234.300, may be sold at such time and in such manner as the issuing authority may determine upon, or such refunding bonds may be issued and delivered in exchange for and upon surrender and cancellation of the bonds to be refunded thereby, with adjustment of interest to be made in cash, if necessary.