FOG, David. Contingency tables and approximate $\chi^2$-distributions. Mathematica Scandinavica, Berkeley, CA, United States, v. 1, p. 93–103, 1953. DOI: 10.7146/math.scand.a-10368. Disponível em: https://journals.msp.org/mscand/article/view/2955. Acesso em: 25 aug. 2026.