(a) Pledging the revenues of the planetarium to secure the payment of the bonds;
(b) The admission fees to be charged for the exhibition of the planetarium and the amount to be raised in each year by admission fees and the use and disposition of such fees and other revenues;
(c) The setting aside of reserves or sinking funds and the regulation or disposition thereof;
(d) The use and exhibition of the planetarium;
(e) Limitations on the purpose to which the proceeds of sale of any issue of bonds then or thereafter to be issued may be applied;
(f) Limitations on the issuance of additional bonds;
(g) The procedure, if any, by which the terms of any contract with bondholders may be amended or abrogated, the amount of bonds the holders of which must consent thereto and the manner in which such consent may be given. 5. Neither the members of the board nor any person executing such bonds shall be liable personally on the bonds or be subject to any personal liability or accountability by reason of the issuance thereof. 6. The Planetarium Authority shall have power out of any funds available therefor to purchase any bonds issued by it at a premium of not more than four percentum and accrued interest. All bonds so purchased shall be cancelled.