GRANLUND, Seppo. An $L^p$-Estimate for the gradient of extremals. MATHEMATICA SCANDINAVICA, [S. l.], v. 50, p. 66–72, 1982. DOI: 10.7146/math.scand.a-11944. Disponível em: https://tidsskrift.dk/math/article/view/11944. Acesso em: 14 aug. 2026.