Witness may refer to memorandum.
Section 338
SEC. 338. Witness may refer to memorandum. — A witness may be allowed to refresh his memory respecting a fact, by anything written by himself or under his direction at the time when the fact occurred, or immediately thereafter, or at any time when the fact was fresh in his memory and he knew that the same was correctly stated in writing; but in such case the writing must be produced and may be seen by the adverse party, who may, if he choose, cross-examine the witness upon it, and may read it in evidence. So, also, a witness may testify from such a writing, though he retain no recollection of the particular facts, if he is able to swear that the writing correctly stated the transaction when made; but such evidence must be received with caution.