NYALUKE, K.W; OKELO, N.B; ONGATI, O. Fredholmness Conditions for Operators Perturbed by Orthogonal Idempotents in Banach Spaces. International Journal of Modern Computation, Information and Communication Technology, [S. l.], v. 3, n. 1, p. 30–35, 2020. DOI: 10.65000/ddvaan18. Disponível em: https://gjpublications.com/index.php/IJMCICT/article/view/53. Acesso em: 5 feb. 2026.