EBANKS, Bruce. The cosine-sine functional equation on semigroups. Annales Mathematicae Silesianae, [S. l.], v. 36, n. 1, p. 30–52, 2021. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/13459. Acesso em: 5 dec. 2025.