A. Any library, college, university, museum or institution of the state or any of its political subdivisions may hold in confidence materials of a historical or educational value upon which the donor or seller has imposed restrictions with respect to access to and inspection of the materials for a definite period of time as specified by the donor or seller.

B. Access to and inspection of such materials may be restricted during the period specified by the donor or seller in the manner specified by the donor or seller.

C. The provisions of Subsections A and B of this section do not apply to materials which were public records of New Mexico as defined in Section 14-2-1 N.M. Stat. Ann. while in the possession of the donor or seller at the time of the donation or sale.