Verkalets, N., and A. Zagorodnyuk. “Linear Subspaces in Zeros of Polynomials on Banach Spaces”. Journal of Vasyl Stefanyk Precarpathian National University 2, no. 4 (December 24, 2015): 105–136. Accessed February 26, 2025. https://vps.pnu.edu.ua/index.php/jpnu/article/view/2644.