Mo. Rev. Stat. § 88.808: Sidewalk improvement — notice (cities, under 10,000).

If the notice in writing cannot be personally served in the state as provided in section 88.806, or if the owner or owners are unknown and cannot be personally served, the council shall cause four weeks' notice to be published in the English language, in some daily or weekly newspaper published in the county in which the property or lot is situated, setting forth all the facts required in the written notice in section 88.806.