DUDKIN, M. Ye. Point spectrum of the schrödinger operator with point interactions at the vertices of regular N-gons. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 56, n. 8, p. 1128–1134, 2004. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3827. Acesso em: 5 dec. 2025.