Testimony to facts stated in document mentioned in section 161
162.  A witness may also testify to facts mentioned in any such document as is mentioned in section 161 although the witness has no specific recollection of the facts themselves, if the witness is sure that the facts were correctly recorded in the document.
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     A book-keeper may testify to facts recorded by him or her in books regularly kept in the course of business if he or she knows that the books were correctly kept, although he or she has forgotten the particular transactions entered.