Bonds issued pursuant to the Nebraska Elementary and Secondary School Finance Authority Act shall not be deemed to constitute a debt of the state or of any political subdivision thereof or a pledge of the faith and credit of the state or of any such political subdivision, but such bonds shall be a limited obligation of the authority payable solely from the funds, securities, or government securities pledged for their payment as authorized in the act unless such bonds are refunded by refunding bonds issued under the act, which refunding bonds shall be payable solely from funds, securities, or government securities pledged for their payment as authorized in the act. All such revenue bonds shall contain on the face thereof a statement to the effect that the bonds, as to both principal and interest, are not an obligation of the State of Nebraska or of any political subdivision thereof but are limited obligations of the authority payable solely from revenue, securities, or government securities, as the case may be, pledged for their payment. All expenses incurred in carrying out the act shall be payable solely from funds provided under the authority of the act, and nothing contained in the act shall be construed to authorize the authority to incur indebtedness or liability on behalf of or payable by the state or any political subdivision thereof.