CHAOHA, P.; INTRAKUL, J.; WICHIRAMALA, W. Lipschitz retractions onto sphere vs spherical cup in a Hilbert space. Topological Methods in Nonlinear Analysis, [S. l.], v. 52, n. 2, p. 677–691, 2018. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2018.034. Acesso em: 3 jul. 2024.