ŠAPUROVAS, A. On the periodicity of composite function. Lithuanian Mathematical Journal, [S. l.], v. 11, n. 1, p. 207–214, 1971. DOI: 10.15388/LMJ.1971.20974. Disponível em: https://journals.vu.lt./LMJ/article/view/20974. Acesso em: 26 apr. 2025.