The bonds shall be signed by the president of the authority and attested by its secretary; and a facsimile of the signatures of both of said officers may be printed or otherwise reproduced on any of the bonds in lieu of being manually signed if the proceedings under which the bonds are issued provides for the manual authentication of such bonds by a trustee or paying agent or by named individuals who are employees of the state and who are assigned to the Department of Finance or Office of the State Treasurer. The seal of the authority shall be impressed on the bonds, and a facsimile of said seal may be printed or otherwise reproduced on any of the bonds in lieu of being manually impressed thereon. Delivery of bonds so executed shall be valid notwithstanding any changes in officers subsequent to the signing of such bonds.