All provisions of this article pertaining to bonds issued under this article that are not inconsistent with the provisions of this section shall, to the extent applicable, also apply to the refunding bonds issued hereunder. The principal proceeds from the sale of any bonds issued hereunder, when not needed for the purposes for which such bonds were issued, and any other moneys received hereunder, when not needed for the purposes for which such moneys may be used, may at the discretion of the director, with the approval of the Governor, be invested in direct general obligations of the United States of America and the earnings on any investment so made shall be used in the same manner that the moneys so invested are herein provided to be used.