53 Pa. Stat. § 25683
When any city of the second class shall issue such non-debt revenue bonds, the authorities thereof may sell the same or any portion thereof at private sale to the United States of America or any agency, instrumentality or corporation thereof, or to the sinking fund of the city. Any bonds not so sold shall be sold to the highest responsible bidder after public notice by advertisement once a week for three weeks in at least one newspaper of general circulation published in the city. No bid for such bonds at less than par value shall be accepted. Where bonds shall be advertised for sale as herein provided and no bids have been received, then it shall be lawful for such city to sell the same at private sale for not less than par value and accrued interest.
53 P.S. § 25683