TVERBERG, Helge. On the Permanent of a Bistochastik Matrix. Mathematica Scandinavica, Berkeley, CA, United States, v. 12, p. 25–35, 1963. DOI: 10.7146/math.scand.a-10669. Disponível em: https://journals.msp.org/mscand/article/view/2655. Acesso em: 25 jul. 2026.