All bonds shall be signed by the chair or vice chair and the secretary or treasurer of the authority and the seal of the authority shall be affixed thereto; provided that a facsimile of the signature of one, but not both, of the officers whose signatures shall appear on the bonds may be imprinted or otherwise reproduced thereon in lieu of his or her manually signing the same; and provided further, that a facsimile of the seal of the authority may be imprinted or otherwise reproduced on the bonds in lieu of being manually affixed thereto. Coupons shall be signed by the chair or vice chair and the secretary or treasurer of the authority, but a facsimile of the signature of such chair or vice chair and such secretary or treasurer may be impressed or otherwise reproduced on any such interest coupons in lieu of their manually signing the same. Delivery of bonds so executed shall be valid notwithstanding any changes in officers or in the seal of the authority after the signing and sealing of the bonds.