Notice of bond elections shall be given by posting notices, signed by not less than a majority of the board, in three public places in the district, at least one of which shall be in each county in which the district is located, not less than 20 days before the election, and by publishing the notice not less than once a week for three successive weeks before the election in a newspaper published in the district, if there is one, and if not, in a newspaper published in each county in which the district is located.