GONÇALVES, Daciberg L.; SPREAFICO, Mauro. The fundamental group of the space of maps from a surface into the projective plane. Mathematica Scandinavica, Berkeley, CA, United States, v. 104, n. 2, p. 161–181, 2009. DOI: 10.7146/math.scand.a-15092. Disponível em: https://journals.msp.org/mscand/article/view/605. Acesso em: 24 jul. 2026.