BAAS, Nils Andreas. On Formal Groups and Singularities in Complex Corbordism Theory. Mathematica Scandinavica, Berkeley, CA, United States, v. 33, p. 303–313, 1973. DOI: 10.7146/math.scand.a-11492. Disponível em: https://journals.msp.org/mscand/article/view/2175. Acesso em: 25 jul. 2026.