The production of documentary material in response to a civil investigative demand served under this article shall be made under a sworn certificate, in such form as the demand designates, by (i) in the case of a natural person, the person to whom the demand is directed, or (ii) in the case of a person other than a natural person, a person having knowledge of the facts and circumstances relating to such production and authorized to act on behalf of such person. The certificate shall state that all of the documentary material required by the demand and in the possession, custody, or control of the person to whom the demand is directed has been produced and made available to the investigator identified in the demand. Any person upon whom any civil investigative demand for the production of documentary material has been served shall make such material available for inspection and copying to the investigator identified in such demand at the principal place of business of such person, or at such other place as the investigator and the person thereafter may agree and prescribe in writing, or as the court may direct. Such material shall be made available on the return date specified in such demand, or on such later date as the investigator may prescribe in writing. Such person may, upon written agreement between the person and the investigator, substitute copies for originals of all or any part of such material.