DOROGOVTSEV, A. Ya. On periodic and bounded solutions of the operator Riccati equation. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 45, n. 2, p. 239–242, 1993. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5804. Acesso em: 14 apr. 2025.