All local public funds received by or credited to an institution shall be disbursed on checks signed by the two officials of the institution who shall have been designated by the board of trustees. The officials so designated shall countersign a check only if the funds required by such check are within the amount of funds remaining to the credit of the institution and are within the unencumbered balance of the appropriation for the item of expenditure according to the approved budgets of the institution. Each check shall be accompanied by an invoice, statement, voucher, or other basic document which indicates, to the satisfaction of the signing officials, that the issuance of such check is proper. (1963, c. 448, s. 23; 1965, c. 488, s. 2; 1979, c. 462, s. 2; c. 896, s. 13; 1979, 2nd Sess., c. 1130, s. 1; 1981, c. 157, s. 1.)