(505 ILCS 100/21) (from Ch. 5, par. 971)
    Sec. 21. All individual notices, service of which is provided for in this Act, shall be in writing. Service of such notices shall be in the same manner as service of a summons in a civil action in the circuit court or by certified mail to the last known address to be ascertained, if necessary, from the last tax list.
(Source: P.A. 77-1037.)