(1)  A witness may, while under examination, refresh his memory by referring to any writing made by himself at the time of the transaction concerning which he is questioned, or so soon afterwards that the Court considers it likely that the transaction was at that time fresh in his memory:

   Provided that the witness may also refer to any such writing made by any other person, and read by the witness within the time aforesaid, if when he read it, he knew it to be correct.

   (2)  Whenever a witness may refresh his memory by reference to any document, he may, with the permission of the Court, refer to a copy of such document:

   Provided that the Court be satisfied that there is sufficient reason for the non-production of the original:

   Provided further that an expert may refresh his memory by reference to professional treatises.