Neb. Rev. Stat. § 14-529

Bonds issued under the authority of the provisions of section 14-528 shall be denominated bonds to finance street improvements, shall be issued and sold in accordance with the provisions of section 14-515 governing the issuance and sale of bonds, and shall bear an interest rate not greater than the rate of interest specified in such section regarding general bonds of the city. Such bonds so issued may be made payable in not less than five years and in not more than twenty years from date of issue.