Semenchuk, A., and R. Zatorsky. “The Fourth Order Mixed Periodic Recurrence Fractions”. Journal of Vasyl Stefanyk Precarpathian National University 2, no. 4 (December 24, 2015): 93–104. Accessed July 3, 2024. https://journals.pnu.edu.ua/index.php/jpnu/article/view/2643.