DERKACH, V. A. On generalized resolvents of Hermitian operators in Krein spaces. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 46, n. 9, p. 1134–1147, 1994. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5630. Acesso em: 5 dec. 2025.