K.S.A. 19-2771

That all bonds issued under the provisions of the next preceding section shall be executed as provided by law; each of said bonds shall recite that it is issued under the provisions of this act, that it is a general obligation bond of the county but that such bond is payable from special assessments that have been levied and constitute a lien upon real estate in said district benefited by improvements made under the provisions of this act, and such recital shall be relied upon by any purchaser of said bonds as conclusive that the same were issued in conformity to this act and that all conditions precedent to their issue were duly performed.