“Browder essential approximate pseudospectrum and defect pseudospectrum on a Banach space: doi:10.17398/2605-5686.34.1.29” (2019) Extracta Mathematicae, 34(1), p. 29–40. Available at: https://revista-em.unex.es/index.php/EM/article/view/2605-5686.34.1.29 (Accessed: 22 December 2024).