(a) The revenue bonds may be payable from, and secured by a pledge of, all or part of the revenues, income, or resources of the board or the board's hospital facilities. Additionally, the bonds may be secured by a mortgage or deed of trust on real or personal property, and the board may authorize the execution and delivery of trust indentures or other encumbrances to evidence the security.
(b) The bonds must contain substantially the following statement: "The owner hereof shall never have the right to demand payment of this obligation from taxes levied by the hospital board."