GONGBAO, L.; MARTIO, O. Stability in Obstacle Problems. MATHEMATICA SCANDINAVICA, [S. l.], v. 75, p. 87–100, 1994. DOI: 10.7146/math.scand.a-12505. Disponível em: https://www.mscand.dk/article/view/12505. Acesso em: 5 may. 2024.