POSILICANO, A. On the common point spectrum of pairs of self-adjoint extensions. Methods of Functional Analysis and Topology, [S. l.], v. 20, n. 1, p. 59–67, 2014. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/567. Acesso em: 16 dec. 2025.