FENILLE, Marcio Colombo. The trivial homotopy class of maps from two-complexes into the real projective plane. Topological Methods in Nonlinear Analysis. Online. 1 December 2015. Vol. 46, no. 2, pp. 603 - 616. [Accessed 27 April 2024]. DOI 10.12775/TMNA.2015.060.