VakarchukS. B., and ZhirS. I. “On the Best Polynomial Approximations of Entire Transcendental Functions of Many Complex Variables in Some Banach Spaces”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 66, no. 12, Dec. 2014, pp. 1598–1614, https://umj.imath.kiev.ua/index.php/umj/article/view/2249.