BodnarD. I., and DmytryshynR. I. “Multidimensional Associated Fractions With Independent variables and Multiple Power Series”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 3 (March 25, 2019): 325-349. Accessed November 30, 2020. http://umj.imath.kiev.ua/index.php/umj/article/view/1442.