1968—Pub. L. 90–492 designated existing provisions as par. (b), added pars. (a), and (c) to (e), and in par. (b), as so designated, extended the types of persons required to maintain records necessary for the enforcement of this chapter, required such persons to give representatives of the Secretary access to their places of business, and opportunity to examine records, facilities, and inventories and to copy records and take inventory samples upon payment.