Licensees shall retain each Form 4473 until business or licensed activity is discontinued, either on paper, or in an electronic alternate method approved by the Director, at the business premises readily accessible for inspection under this part. Paper forms over 20 years of age may be stored at a separate warehouse, which shall be considered part of the business premises for this purpose and subject to inspection under this part. Forms 4473 shall be retained in the licensee's records as provided in § 478.124(b), provided that Forms 4473 with respect to which a sale, delivery, or transfer did not take place shall be separately retained in alphabetical (by name of transferee) or chronological (by date of transferee's certification) order.