SATO, Ken-ichi. A remark on the criteria for 3 to be a ninth power (mod $p$). Mathematica Scandinavica, Berkeley, CA, United States, v. 60, p. 148–150, 1987. DOI: 10.7146/math.scand.a-12177. Disponível em: https://journals.msp.org/mscand/article/view/1449. Acesso em: 25 jul. 2026.