Section 8L. Every public charity required to file written annual reports with the division pursuant to section eight F shall, in accordance with rules and regulations prescribed by the division, keep true fiscal records as to its activities within the commonwealth in such form as will enable it accurately to provide the information required by said section. Upon demand, such records shall be made available to the division for inspection. Such records shall be retained for a period of at least three years after the end of the period to which the annual report relates.