MOLYBOGA, V. M.; MIKHAILETS, V. A. Spectral gaps of one-dimensional Schrödinger operators with singular periodic potentials. Methods of Functional Analysis and Topology, [S. l.], v. 15, n. 1, p. 31–40, 2009. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/406. Acesso em: 16 dec. 2025.