(2) When the statement was made by such person in the ordinary course of business, and in particular when it consists of any entry or memorandum made by him in books kept in the ordinary course of business, or in the discharge of professional duty; or of an acknowledge-ment written or signed by him of the receipt of money, goods, securities or property of any kind; or of a document used in commerce written or signed by him; or of the date of a letter or other document usually dated, written or signed by him.