PONOMARENKO, Yu. A.; Tіman M. F. On absolute summability of multiple Fourier series . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 23, n. 3, p. 346–361, 1971. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8561. Acesso em: 6 dec. 2025.