RAMM, A. G.; GESZTESY, F. An inverse problem for point inhomogeneities. Methods of Functional Analysis and Topology, [S. l.], v. 6, n. 2, p. 1–12, 2000. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/114. Acesso em: 17 dec. 2025.