POSILICANO, A. Boundary triples and Weyl functions for singular perturbations of self-adjoint operators. Methods of Functional Analysis and Topology, [S. l.], v. 10, n. 2, p. 57–63, 2004. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/241. Acesso em: 17 dec. 2025.