Gorgula, V. I., and N. I. Nagnibida. “On a Special Polynomial Basis of Analytical functions’ Space ”. Ukrains’kyi Matematychnyi Zhurnal, vol. 40, no. 1, Dec. 1987, pp. 39-42, https://umj.imath.kiev.ua/index.php/umj/article/view/9051.