FERREYA, E.; GODOY, T.; URCIUOLO, M. $L^p-L^q$ estimates for singular fractional integral operators. Mathematica Scandinavica, Berkeley, CA, United States, v. 84, n. 2, p. 213–230, 1999. DOI: 10.7146/math.scand.a-13876. Disponível em: https://journals.msp.org/mscand/article/view/952. Acesso em: 25 jul. 2026.