REICH, S.; ZASLAVSKI, A. J. Well-posedness and porosity in best approximation problems. Topological Methods in Nonlinear Analysis, [S. l.], v. 18, n. 2, p. 395–408, 2001. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2001.041. Acesso em: 14 dec. 2024.