GLADKIVS’KA, O. V. An example of a complete orthonormal system in a Hilbert space of generalized functions. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 5, p. 725–728, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5055. Acesso em: 6 dec. 2025.