Neb. Rev. Stat. § 14-3,120

If the certificates required by section 14-3,119 show that the petition is regular, legal, and sufficient the city shall cause a copy of the petition to be published for three days in the official newspaper of the city with a notice directing the property owners generally in the improvement district that they shall have thirty days from the first day of publication of the petition and notice to file a protest with the city against the regularity or the sufficiency of the petition or signatures on such petition.