Admissibility of tax records: entries in income-tax authority custody are evidence and may be proved by originals or certified copies. Entries in records or other documents in the custody of an income-tax authority are admissible in evidence in prosecutions under this Chapter and may be proved either by producing the original records or by producing a copy certified by the custody-holding income-tax authority under its signature stating it is a true copy and that the originals are in its custody.