715 ILCS 5/1

When any notice shall be required by law, or the order of court, or by any contract, to be published in any newspaper, and no other mode of proving the same is provided, the certificate of the publisher, by himself or his authorized agent, with a written or printed copy of such notice annexed, stating the number of times which the same shall have been published, and the dates of the first and last papers containing the same, shall be sufficient evidence of the publication therein set forth. The certificate shall also contain the further certificate of the publisher, by himself or his authorized agent, stating that the newspaper is a newspaper as hereinafter defined.