Any issue of bonds may be sold at 1 time or in installments at different times. The maturities of an installment of bonds offered for sale when combined with all maturities of the issue previously sold, shall be such as to comply with requirements as to maturities of a single issue of bonds. Any unsold part of an issue or installment may be sold notwithstanding that the maturities thereof, when considered alone, do not comply with such requirements.
N.J.S. § 40A:2-33