How can the contents of a document be proved?

1) Trial Court on 30.01.2019 has ordered that- “Considering the admission & denial of defendants the documents filed were given Article numbers 1 to 4 instead of exhibits”. 2) Trial Court but afterwards on next date 31.01.2019 again passed 2nd Order that- “In view of findings recorded by Hon’ble Appellate Court, the certified copies of Article 1 to 4 are Public Documents. They are admitted into evidences. Hence exhibited as Exh. 96 to 99”. 3) The said 2nd order dated 31.01.2019 of Trial Court admitting documents into evidence hence exhibiting same is not challenged by Defendants till now. Query: a) Whether Plaintiff, for proving his case, can rely on CONTENTS of said documents without proving contents, because the Defendants has not challenged the 2nd order of 31.01.2019 specifically passed by Trial Court admitting documents into evidences hence exhibiting same?