SANKER, David. The converse to Alexandre Froda’s irrationality criterion. Mathematica Scandinavica, Berkeley, CA, United States, v. 68, p. 5–18, 1991. DOI: 10.7146/math.scand.a-12341. Disponível em: https://journals.msp.org/mscand/article/view/1289. Acesso em: 24 jul. 2026.