DERKACH, V. A.; HASSI, S.; DE SNOO, H. Operator models associated with Kac subclasses of generalized Nevanlinna functions. Methods of Functional Analysis and Topology, [S. l.], v. 5, n. 1, p. 65–87, 1999. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/81. Acesso em: 18 dec. 2025.