NIZHNIK, L. P.; BRASCHE, J. F. One-dimensional Schrödinger operators with general point interactions. Methods of Functional Analysis and Topology, [S. l.], v. 19, n. 1, p. 4–15, 2013. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/531. Acesso em: 16 dec. 2025.