STEGEMAN, J. D. On a Theorem of N.Th. Varopoulos. Mathematica Scandinavica, Berkeley, CA, United States, v. 27, p. 50–52, 1970. DOI: 10.7146/math.scand.a-10986. Disponível em: https://journals.msp.org/mscand/article/view/2342. Acesso em: 25 jul. 2026.