Texas Government Code - GOV'T § 313.004. Proof of Publication or Posting

(a) If publication of notice in a newspaper is required by law, proof of publication shall be made by the affidavit of the publisher accompanied by a printed copy of the notice as published.

(b) Proof of posting may be made by the return of the sheriff or constable or by the affidavit of a credible person made on a copy of the posted notice showing the fact of the posting.