CVETKOVIĆ, A. S.; MILOVANOVIĆ, G. V.; STANIĆ, M. P. Positive Solutions of a Class of Operator Equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 67, n. 2, p. 245–260, 2015. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1977. Acesso em: 5 dec. 2025.