EROVENKO, V. A. Some results on essential spectra of differential operators in Banach spaces. Mathematical Modelling and Analysis, [S. l.], v. 8, n. 3, p. 203–216, 2003. DOI: 10.3846/13926292.2003.9637224. Disponível em: https://journals.vilniustech.lt/index.php/MMA/article/view/9778. Acesso em: 9 may. 2025.