Dovgoshei, A. A. “Chebyshev Polynomial Approximation on a Closed Subset With Unique Limit Point and Analytic Extension of Functions”. Ukrains’kyi Matematychnyi Zhurnal 48, no. 7 (July 25, 1996): 891–900. Accessed April 14, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/5261.