DIEU, N. Q.; LONG, T. van. Sublevel sets of certain extremal functions. MATHEMATICA SCANDINAVICA, [S. l.], v. 101, n. 2, p. 184–194, 2007. DOI: 10.7146/math.scand.a-15039. Disponível em: https://www.mscand.dk/article/view/15039. Acesso em: 2 may. 2024.