HEFTER, S. L.; PIVEN’ , O. L. Infinite order differential operators in the module of formal generalized functions and in a ring of formal power series. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 74, n. 6, p. 784–799, 2022. DOI: 10.37863/umzh.v74i6.6955. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/6955. Acesso em: 5 dec. 2025.