Zatorsky, R.A., and A.V. Semenchuk. “Calculation Algorithm of Rational Estimations of Recurrence Periodical Fourth Order Fraction”. *Carpathian Mathematical Publications* 6, no. 1 (July 19, 2014): 32–43. Accessed May 20, 2024. https://journals.pnu.edu.ua/index.php/cmp/article/view/1332.