In the performance of its duties under Articles 1 through 13 of this chapter the Commission, any commissioner or any agent or employee of the Commission with written authority from the Commission authenticated by its seal 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.