Low and High Frequency Convergence of the Spectrum of Some Self-Adjoint Compact Operator that Depends on a Small Parameter. Neliniini Kolyvannya, [S. l.], v. 4, n. 2, p. 241–251, 2001. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/168. Acesso em: 22 jan. 2026.