BLAHOTA, István. Approximation of double Walsh–Fourier series by means of the matrix transform. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 76, n. 5, p. 664–679, 2024. DOI: 10.3842/umzh.v76i5.7397. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/7397. Acesso em: 5 dec. 2025.