CALDERBANK, David M. J. The Faraday 2-form in Einstein-Weyl geometry. Mathematica Scandinavica, Berkeley, CA, United States, v. 89, n. 1, p. 97–116, 2001. DOI: 10.7146/math.scand.a-14332. Disponível em: https://journals.msp.org/mscand/article/view/873. Acesso em: 24 jul. 2026.