LASURIYA, R. A.; STEPANETS, O. I. Strong summability of orthogonal expansions of summable functions. II. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 48, n. 3, p. 393–405, 1996. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5336. Acesso em: 5 dec. 2025.