JAFAR, Ahmed; AJEBBAR, Omar; ELQORACHI, Elhoucien. A Kannappan-cosine functional equation on semigroups. Annales Mathematicae Silesianae, [S. l.], v. 39, n. 1, p. 143–154, 2024. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/17430. Acesso em: 16 dec. 2025.