MARTYNYUK, D. I. Integration of linear differential equations with a devicating argument by means of series . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 18, n. 5, p. 105–111, 1966. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8447. Acesso em: 6 dec. 2025.