WEGULO, M.E.O; AYWA, S; OKELO, N.B. On spectra of n-hyponormal operators in Hilbert space. International Journal of Modern Computation, Information and Communication Technology, [S. l.], v. 2, n. 7, p. 53–58, 2019. DOI: 10.65000/esjrq525. Disponível em: https://gjpublications.com/index.php/IJMCICT/article/view/43. Acesso em: 23 oct. 2025.