Section 517.   PUBLISHING OF LEGAL NOTICES.
   The City Council shall contract for the publication of all legal notices, ordinances and other matter required to be published in a newspaper of general circulation in the City. Each such contract shall cover a period of not less than one nor more than three years. In the event there is more than one newspaper of general circulation published within the City, the contract shall be made only after the publication of a notice inviting bids therefor. In the event there is only one newspaper of general circulation published in the City, then the City Council shall have the power to contract with such newspaper for the printing and publishing of such legal notices or matter without being required to advertise for bids therefor. The newspaper with which any such contract is made shall be the official newspaper for the publication of such notices or other matter for the period of such contract.
   In no case shall the contract prices for such publication exceed the customary rates charged by such newspaper for the publication of legal invoices of a private character.
   In the event there is no newspaper of general circulation published in the City, or in the event no such newspaper will accept such notices or other matter at the rates permitted herein, then all legal notices or other matter may be published by posting copies thereof in at least three public places in the City to be designated by ordinance.
   No defect or irregularity in proceedings taken under this Section, or failure to designate an official newspaper, shall invalidate any publication where the same is otherwise in conformity with this Charter or law or ordinance.