In the performance of its duties under Articles 1 through 13 of this chapter, any employee or agent of the Office of Regulatory Staff may inspect or make copies of all income, property, or other tax returns, reports or other information filed by telephone utilities with or otherwise obtained by any other department, commission, board, or agency of the state government and all such other departments, commissions, boards, or agencies of the state government shall permit such inspection or the making of such copies.