Nebraska Revised Statute 14-3,105
Before any sidewalk shall be constructed or repaired by the city, the owner or owners of the lots or lands to be assessed shall be given notice to construct or repair such sidewalk and shall have twenty days after the giving of such notice within which to construct or repair the same. Such notice shall be served or published as directed by ordinance and if the notice be by publication it shall be sufficient to address such notice to the owners generally. The city shall give an additional notice by registered letter or certified mail directed to the last-known address of such owners or their agents, but failure to give such additional notice shall not invalidate the proceedings, or the special assessments for such sidewalk.
Laws 1959, c. 36, § 22, p. 203.