Gilewicz, J. 1994. “Story of Rational Approximation for the Class of Stieltjes Functions: From Stieltjes to Recent Optimal Estimations of Errors”. Ukrains’kyi Matematychnyi Zhurnal 46 (7): 941–943. https://umj.imath.kiev.ua/index.php/umj/article/view/5686.