@article{articled1effd21,
title   = {A useful lemma on equivariant maps},
author = {Gonçalves, Daciberg Lima and Skopenkov, A},
year = {2014},
doi = {10.4310/HHA.2014.v16.n2.a17},
journal   = {Homology, Homotopy and Applications}
}