AMMAR, A.; JERIBI, A.; MAHFOUDHI, K. Measure of noncompactness, essential approximation and defect pseudospectrum. Methods of Functional Analysis and Topology, [S. l.], v. 25, n. 1, p. 1–11, 2019. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/708. Acesso em: 16 dec. 2025.