BRANSON, Thomas P. Differential operators cononically associated to a conformal structure. Mathematica Scandinavica, Berkeley, CA, United States, v. 57, p. 293–345, 1985. DOI: 10.7146/math.scand.a-12120. Disponível em: https://journals.msp.org/mscand/article/view/1548. Acesso em: 25 jul. 2026.