Every bond provided for in this chapter must be a negotiable instrument and must bear interest at a rate or rates resulting in an average annual net interest rate which must not exceed twelve percent per annum if the bonds are sold at private sale. There is no interest rate ceiling on bonds sold at public sale or to the state of North Dakota or any of its agencies or instrumentalities. Each bond must specify the time and place of payment of the principal.
N.D.C.C. § 61-08-07