CHANDOK, S. Arbitrary binary relations, contraction mappings and $b$-metric spaces. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 72, n. 4, p. 565–574, 2020. DOI: 10.37863/umzh.v72i4.368. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/368. Acesso em: 7 apr. 2025.