(a) A credit union shall have the power to establish offices at locations other than its main office if the maintenance of those offices is reasonably necessary to furnish services to its membership. No additional offices shall be established to serve persons who are not entitled to membership, as defined in the common bond provision of the articles of incorporation, and who would not be entitled to services of the credit union at its main office.
(b) All books of account shall be maintained at the main office of the credit union.
(c) The State Credit Union Supervisor shall grant prior written approval for the establishment of subsidiary offices. He or she shall have the authority to issue notice and hold a public hearing to determine if the establishment of the subsidiary office or offices is necessary and in the best interests of the credit union.