30 CFR §1212.200

1. (a)All records pertaining to Federal and Indian solid minerals leases shall be maintained by a lessee, operator, revenue payor, or other person for 6 years after the records are generated unless the record holder is notified, in writing, that records must be maintained for a longer period. When an audit or investigation is underway, records shall be maintained until the record holder is released by written notice of the obligation to maintain records.
2. (b)The ONRR shall have access to all records of the operator/lessee pertaining to compliance to Federal royalties, including, but not limited to:
   1. (1)Qualities and quantities of all products mined, processed, sold, delivered, or used by the operator/lessee.
   2. (2)Prices received for mined or processed products, prices paid for like or similar products, and internal transfer prices.
   3. (3)Costs of mining, processing, handling, and transportation.