KLOVE, T. Periodicity of Recurring Sequences in Rings. MATHEMATICA SCANDINAVICA, [S. l.], v. 32, p. 165–168, 1973. DOI: 10.7146/math.scand.a-11452. Disponível em: https://www.mscand.dk/article/view/11452. Acesso em: 5 may. 2024.