KLOVE, Torleiv. Periodicity of Recurring Sequences in Rings. Mathematica Scandinavica, Berkeley, CA, United States, v. 32, p. 165–168, 1973. DOI: 10.7146/math.scand.a-11452. Disponível em: https://journals.msp.org/mscand/article/view/2156. Acesso em: 25 jul. 2026.