Mafra, Albetã C., and Marcelo Tavares. “A Criterion for Bijectivity of Mappings of Euclidean Spaces”. Topological Methods in Nonlinear Analysis 43, no. 1 (April 12, 2016): 117–128. Accessed April 26, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2014.008.