Ribeiro, Jarne D, and Evandro Monteiro. “Brouwer’s Topological Degree: Theory and Applications”. Sigmae 1, no. 1 (December 31, 2012): 152–160. Accessed April 27, 2024. https://publicacoes.unifal-mg.edu.br/revistas/index.php/sigmae/article/view/101.