HEMBARS'KA, S. B.; ZADEREI, P. V. Estimations of the integral of modulus for mixed derivatives of the sum of double trigonometric series. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 68, n. 7, p. 908–921, 2016. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1890. Acesso em: 5 dec. 2025.