No bonds may be refunded unless the holders thereof voluntarily surrender them for exchange or payment, or unless they either mature or are callable for prior redemption under their terms within twentyfive years from the date of issuance of the refunding bonds. Provision shall be made for paying the bonds being refunded within the period of time.

Source: SL 1974, ch 54, § 5; SDCL Supp, § 6-8A-5; SL 1984, ch 43, § 27.