NIZHNIK, L. P.; ALBEVERIO, S. Schrödinger operators with nonlocal potentials. Methods of Functional Analysis and Topology, [S. l.], v. 19, n. 3, p. 199–210, 2013. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/548. Acesso em: 16 dec. 2025.