KAIRIES, H.-H. On continuous and residual spectra of operators connected with iterative functional equations. Annales Universitatis Paedagogicae Cracoviensis Studia Mathematica, [S. l.], v. 5, p. 51–57, 2006. Disponível em: https://studmath.uken.krakow.pl/article/view/13292. Acesso em: 30 oct. 2026.