SOLONUKHA, O.V. On the existence of solutions of operator differential equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 56, n. 6, p. 837–850, 2004. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3802. Acesso em: 5 dec. 2025.