Okla. Stat. tit. 17, § 17-154: Records of public utility business

In case the owner or operator of any public utility is engaged

in carrying on any other business in connection with the operation

of such public utility, the Commission may require the cost of the

operation and gross revenues of such joint business to be kept in

such form and manner as may be prescribed by the Commission so that

the cost of the operation and gross revenues of the public utility

may be ascertained.