An authority shall not acquire any existing parking facility by the exercise of the power of eminent domain except after public hearing. Notice of the date, time, place, and purpose of the hearing shall be published once not less than 10 nor more than 20 days prior to the hearing in a newspaper of general circulation printed and published in the city, or, if there be no such newspaper printed and published therein, by posting copies of the notice in at least three public places in the city not less than 10 nor more than 20 days prior to the date of the hearing.