Except as otherwise expressly provided in sections 13a-239 to 13a-246, inclusive, all of said bonds shall be issued in accordance with § 3-20 and be sold at a price not less than the principal amount thereof plus accrued interest, and the proceeds of any sale of said bonds shall be deposited in a special fund and used and applied as provided in said § 3-20. Pending the use or application of any such proceeds as hereinabove directed, such proceeds may be invested by the Treasurer in bonds or obligations of, or guaranteed by, the state or the United States or agencies or instrumentalities of the United States.