The board shall maintain books of account covering revenues derived by it from all sources, together with accounts of all expenses incurred in connection with the carrying out by the board of its purposes as established by and under the terms of this chapter. The board may obtain the services of a certified public accountant for annual audits in lieu of audits conducted by the Department of Examiners of Public Accounts. All such audits shall be filed with the Department of Examiners of Public Accounts and open for public inspection.