KUO, Chung-Cheng. Perturbations of local C-cosine functions. Studia Universitatis Babeș-Bolyai Mathematica, [S. l.], v. 65, n. 4, p. 585–597, 2020. DOI: 10.24193/subbmath.2020.4.08. Disponível em: https://studia.reviste.ubbcluj.ro/index.php/subbmathematica/article/view/2611. Acesso em: 19 apr. 2025.