Section 12. Revenue bonds or notes issued under the provisions of this chapter shall not be deemed to constitute a debt or liability of the commonwealth or of any political subdivision thereof or a pledge of the faith and credit of the commonwealth or of any such political subdivision, but shall be payable solely from the funds herein provided therefor from revenues. All such revenue bonds or notes shall contain on the face thereof a statement to the effect neither the commonwealth nor the Authority shall be obligated to pay the same or the interest thereon except from revenues of the education loan program or programs or the portion thereof for which they are issued and that neither the faith and credit nor the taxing power of the commonwealth or of any political subdivision thereof is pledged to the payment of the principal of or the interest on such bonds or notes. The issuance of revenue bonds or notes under the provisions of this chapter shall not directly or indirectly or contingently obligate the commonwealth or any political subdivision thereof to levy or to pledge any form of taxation whatever therefor or to make any appropriation for their payment.