Neb. Rev. Stat. §§ 23-3570
Any hospital district which has heretofore voted and issued, or which shall hereafter vote and issue, bonds to build or furnish a hospital, or for any other purpose, and which bonds, or any part thereof, still remain unpaid and remain and are a legal liability against such district and are bearing interest, may issue coupon bonds to be substituted in place of, and exchanged for such bonds heretofore issued, whenever such hospital district can effect such substitution and exchange at a rate of not to exceed dollar for dollar or such bonds may be sold for cash where such bonds heretofore issued are subject to the right of redemption at the time the refunding bonds are issued. All bonds issued under the provisions of sections 23-3570 to 23-3572 must, on their face, contain a clause that the district issuing such bonds shall have the right to redeem such bonds at the expiration of five years from the date of the issuance thereof.
Neb. Rev. Stat. §§ 23-3570