Blahota, István. “Approximation of Double Walsh–Fourier Series by Means of the Matrix Transform”. Ukrains’kyi Matematychnyi Zhurnal 76, no. 5 (June 2, 2024): 664–679. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/7397.