Neb. Rev. Stat. § 72-259.05

There shall be filed forthwith, in the office of the register of deeds of the proper county, (1) a plat of such territory certified by the State Surveyor, (2) a certified copy of the resolution of the Board of Educational Lands and Funds approving the same and requesting the annexation, and (3) a copy of the ordinance declaring such annexation, certified under the seal of the city. Thereupon, such annexation of such adjacent territory shall be deemed complete, and the territory included and described in the plat shall be deemed and held to be a part of the city.