Stevic, S. 2003. “A Note on the Recursive Sequence $x_{n + 1} = p_kx_n + p_{k − 1}x_{n − 1} +. + p_1x_{n − K + 1}$”. Ukrains’kyi Matematychnyi Zhurnal 55 (4), 570-74. https://umj.imath.kiev.ua/index.php/umj/article/view/3932.