CEGRELL, U.; KOLODZIEJ, S.; LEVENBERG, N. Two problems on potential theory for unbounded sets. Mathematica Scandinavica, Berkeley, CA, United States, v. 83, n. 2, p. 265–276, 1998. DOI: 10.7146/math.scand.a-13855. Disponível em: https://journals.msp.org/mscand/article/view/973. Acesso em: 25 jul. 2026.